magento#589: Add a tutorial for the checkout workflow

Author: atwixfirster

guides/v2.3/graphql/tutorials/checkout/checkout-add-product-to-cart.md

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+---
+layout: tutorial
+group: graphql
+title: Step 3. Add product to cart
+subtitle: GraphQl checkout tutorial
+return_to:
+  title: GraphQl checkout tutorial
+  url: graphql/tutorials/index.html
+menu_order: 3
+contributor_name: Atwix
+contributor_link: https://www.atwix.com/
+---
+
+**Request**
+```text
+mutation addSimpleProductsToCart(
+  $cart_id: String!
+  $qty: Float!
+  $sku: String!
+) {
+  addSimpleProductsToCart(
+    input: {
+      cart_id: $cart_id
+      cartItems: {
+        customizable_options: []
+        data: {
+          qty: $qty
+          sku: $sku
+        }
+      }
+    }
+  ) {
+    cart {
+      items {
+        id
+        product {
+          sku
+          stock_status
+        }
+        qty
+      }
+    }
+  }
+}
+```
+
+**Response**
+```json
+```

guides/v2.3/graphql/tutorials/checkout/checkout-billing-address.md

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+---
+layout: tutorial
+group: graphql
+title: Step 5. Set billing address
+subtitle: GraphQl checkout tutorial
+return_to:
+  title: GraphQl checkout tutorial
+  url: graphql/tutorials/index.html
+menu_order: 5
+contributor_name: Atwix
+contributor_link: https://www.atwix.com/
+---
+
+**Request**
+```text
+```
+
+**Response**
+```json
+```

guides/v2.3/graphql/tutorials/checkout/checkout-customer.md

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+---
+layout: tutorial
+group: graphql
+title: Step 1. Define customer
+subtitle: GraphQl checkout tutorial
+return_to:
+  title: GraphQl checkout tutorial
+  url: graphql/tutorials/index.html
+menu_order: 1
+contributor_name: Atwix
+contributor_link: https://www.atwix.com/
+---
+
+Customers can make purchases in two ways:
+- As a logged-in user
+- As a guest user who does not create an account
+
+If you want to place order as guest then skip this step.
+
+If you want to place order as a new customer then you should use `createCustomer` mutation to register new customer in the store.
+
+**Request**
+```text
+mutation {
+  createCustomer(
+    input: {
+      firstname: "Bob"
+      lastname: "Loblaw"
+      email: "[email protected]"
+      password: "b0bl0bl@w"
+      is_subscribed: true
+    }
+  ) {
+    customer {
+      id
+      firstname
+      lastname
+      email
+      is_subscribed
+    }
+  }
+}
+```
+
+**Response**
+```json
+{
+  "data": {
+    "createCustomer": {
+      "customer": {
+        "id": 5,
+        "firstname": "Bob",
+        "lastname": "Loblaw",
+        "email": "[email protected]",
+        "is_subscribed": true
+      }
+    }
+  }
+}
+```
+
+Check this ["Customer endpoint"]({{ page.baseurl }}/graphql/reference/customer.html#create-a-customer) page to get the additional information.
+
+If you want to place order as a new customer or a registered customer then you should get customer's authorization token. Use `generateCustomerToken` mutation for that.
+**Request**
+```text
+mutation {
+  generateCustomerToken(email: "[email protected]", password: "b0bl0bl@w") {
+    token
+  }
+}
+``` 
+
+**Response**
+```json
+{
+   "data": {
+     "generateCustomerToken": {
+       "token": "hoyz7k697ubv5hcpq92yrtx39i7x10um"
+     }
+   }
+ }
+``` 
+
+See ["Get customer authorization token"]({{ page.baseurl }}/graphql/get-customer-authorization-token.html) topic to get more details.

guides/v2.3/graphql/tutorials/checkout/checkout-payment-method.md

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+---
+layout: tutorial
+group: graphql
+title: Step 7. Set payment method
+subtitle: GraphQl checkout tutorial
+return_to:
+  title: GraphQl checkout tutorial
+  url: graphql/tutorials/index.html
+menu_order: 7
+contributor_name: Atwix
+contributor_link: https://www.atwix.com/
+---
+
+Use the following query to get all available payment methods for your order.
+
+**Request**
+```text
+{
+  cart(cart_id: "$maskedQuoteId") {
+    available_payment_methods {
+      code
+      title
+    }
+  }
+}
+```
+
+**Response**
+```json
+```

guides/v2.3/graphql/tutorials/checkout/checkout-place-order.md

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+---
+layout: tutorial
+group: graphql
+title: Step 8. Place order
+subtitle: GraphQl checkout tutorial
+return_to:
+  title: GraphQl checkout tutorial
+  url: graphql/tutorials/index.html
+menu_order: 8
+contributor_name: Atwix
+contributor_link: https://www.atwix.com/
+---
+
+**Request**
+```text
+mutation placeOrder(
+  $cart_id: String!
+) {
+  placeOrder(
+    input: {
+      cart_id: $cart_id
+    }
+  ) {
+    order {
+      order_id
+    }
+  }
+}
+```
+
+**Response**
+```json
+```

guides/v2.3/graphql/tutorials/checkout/checkout-shipping-address.md

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+---
+layout: tutorial
+group: graphql
+title: Step 4. Set shipping address
+subtitle: GraphQl checkout tutorial
+return_to:
+  title: GraphQl checkout tutorial
+  url: graphql/tutorials/index.html
+menu_order: 4
+contributor_name: Atwix
+contributor_link: https://www.atwix.com/
+---
+
+**Request**
+```text
+```
+
+**Response**
+```json
+```

guides/v2.3/graphql/tutorials/checkout/checkout-shipping-method.md

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+---
+layout: tutorial
+group: graphql
+title: Step 6. Set shipping method
+subtitle: GraphQl checkout tutorial
+return_to:
+  title: GraphQl checkout tutorial
+  url: graphql/tutorials/index.html
+menu_order: 6
+contributor_name: Atwix
+contributor_link: https://www.atwix.com/
+---
+
+Use `cart` query to retrieve available shipping methods for your quote.
+**Request**
+```text
+query {
+  cart (cart_id: "{$maskedQuoteId}") {
+    shipping_addresses {
+        available_shipping_methods {
+          amount
+          base_amount
+          carrier_code
+          carrier_title
+          error_message
+          method_code
+          method_title
+          price_excl_tax
+          price_incl_tax
+        }
+    }
+  }
+}
+```
+
+**Response**
+```json
+
+```
+
+Use `setShippingMethodsOnCart` mutation query to define a shipping method for your order.
+
+**Request**
+The following mutation query assigns UPS "Ground" method. 
+```text
+mutation {
+  setShippingMethodsOnCart(input: {
+    cart_id: "$maskedQuoteId"
+    shipping_methods: [
+      {
+        cart_address_id: $shippingAddressId
+        carrier_code: "ups"
+        method_code: "GND"
+      }
+    ]
+  }) {
+    cart {
+      shipping_addresses {
+        selected_shipping_method {
+          carrier_code
+          method_code
+          label
+        }
+      }
+    } 
+  }
+}
+```
+
+**Response**
+```json
+
+```

guides/v2.3/graphql/tutorials/checkout/checkout-shopping-cart.md

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+---
+layout: tutorial
+group: graphql
+title: Step 2. Create empty cart
+subtitle: GraphQl checkout tutorial
+return_to:
+  title: GraphQl checkout tutorial
+  url: graphql/tutorials/index.html
+menu_order: 2
+contributor_name: Atwix
+contributor_link: https://www.atwix.com/
+---
+
+**Request**
+This mutation query creates an empty cart:
+```text
+mutation {
+  createEmptyCart
+}
+```
+
+**Response**
+```json
+{
+  "data": {
+    "createEmptyCart": "gqjcFzgL8hNxxdrqLDEkMP487nOWBXOv"
+  }
+}
+```
+
+If you create a shopping cart for the registered customer then you should send customer's authorization token in the `Authorization` parameter of the header:
+
+![GraphiQL Authorization Bearer]({{ page.baseurl }}/graphql/images/graphql-authorization.png)

guides/v2.3/graphql/tutorials/index.md

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+---
+group: graphql
+title: GraphQl checkout tutorial
+contributor_name: Atwix
+contributor_link: https://www.atwix.com/
+---
+
+This tutorial provides information how you can place order through GraphQl. Customers can make purchases in two ways:
+- As a logged-in user
+- As a guest user who does not create an account
+ 
+Basically checkout process in GraphQl consists of the next steps: 
+- define customer (create customer or use registered customer account or place order as guest) 
+- create empty cart
+- add a product to cart
+- set shipping address
+- set billing address
+- set shipping method
+- set payment method
+- place order
+
+//setQuoteEmail