Add wget instructions for systems without curl (#8630)

## Summary
Adds wget instructions for linux installations that don't come with
`curl`.

## Test Plan
This was tested on Ubuntu 20.04, Ubuntu 22.04, Ubuntu 24.04, and Debian
11.

---------

Co-authored-by: Zanie Blue <[email protected]>

Author: joshmcorreia

docs/getting-started/installation.md

@@ -10,26 +10,36 @@ uv provides a standalone installer to download and install uv:
 
 === "macOS and Linux"
 
+    Use `curl` to download the script and execute it with `sh`:
+
     ```console
     $ curl -LsSf https://astral.sh/uv/install.sh | sh
     ```
 
-=== "Windows"
+    If your system doesn't have `curl`, you can use `wget`:
 
     ```console
-    $ powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"
+    $ wget -qO- https://astral.sh/uv/install.sh | sh
     ```
 
-Request a specific version by including it in the URL:
-
-=== "macOS and Linux"
+    Request a specific version by including it in the URL:
 
     ```console
     $ curl -LsSf https://astral.sh/uv/0.5.1/install.sh | sh
     ```
 
 === "Windows"
 
+    Use `irm` to download the script and execute it with `iex`:
+
+    ```console
+    $ powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"
+    ```
+
+    Changing the [execution policy](https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_execution_policies?view=powershell-7.4#powershell-execution-policies) allows running a script from the internet.
+
+    Request a specific version by including it in the URL:
+
     ```console
     $ powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/0.5.1/install.ps1 | iex"
     ```