docs: alpha -> beta (#22)

Author: scottbedard

README.md

@@ -1,6 +1,6 @@
 # vue-cli-plugin-vue-next
 
-A Vue CLI plugin for trying out the Vue 3 alpha.
+A Vue CLI plugin for trying out the Vue 3 beta.
 
 This is for preview purposes only. There might be bugs and undocumented behavior differences from v2, which are expected.
 
@@ -15,7 +15,7 @@ vue add vue-next
 
 ## What's implemented?
 
-- [x] Add Vue 3 alpha and `@vue/compiler-sfc` to the project dependencies.
+- [x] Add Vue 3 beta and `@vue/compiler-sfc` to the project dependencies.
 - [x] Configure webpack to compile `.vue` files with the new Vue 3 compiler.
 - [x] [Codemods](./generator/codemods/global-api) that automatically migrate some global API changes mentioned in [RFC-0009](https://github.com/vuejs/rfcs/blob/master/active-rfcs/0009-global-api-change.md).
 - [x] Install Vuex 4.0 & Vue Router 4.0 in the project, if older versions of them are detected.