[Updates] Automated vendor dotnet-install script (#801)

* Automated dotnet-install script update

* Bump version

---------
Co-authored-by: github-actions <github-actions@github.com>
Co-authored-by: Samruddhi Khandale <skhandale@microsoft.com>

src/dotnet/devcontainer-feature.json

 {
     "id": "dotnet",
-    "version": "2.0.2",
+    "version": "2.0.3",
     "name": "Dotnet CLI",
     "documentationURL": "https://github.com/devcontainers/features/tree/main/src/dotnet",
     "description": "This Feature installs the latest .NET SDK, which includes the .NET CLI and the shared runtime. Options are provided to choose a different version or additional versions.",

src/dotnet/scripts/vendor/dotnet-install.sh

@@ -1708,7 +1708,11 @@ do
         -?|--?|-h|--help|-[Hh]elp)
             script_name="$(basename "$0")"
             echo ".NET Tools Installer"
-            echo "Usage: $script_name [-c|--channel <CHANNEL>] [-v|--version <VERSION>] [-p|--prefix <DESTINATION>]"
+            echo "Usage:"
+            echo "       # Install a .NET SDK of a given Quality from a given Channel"
+            echo "       $script_name [-c|--channel <CHANNEL>] [-q|--quality <QUALITY>]"
+            echo "       # Install a .NET SDK of a specific public version"
+            echo "       $script_name [-v|--version <VERSION>]"
             echo "       $script_name -h|-?|--help"
             echo ""
             echo "$script_name is a simple command line interface for obtaining dotnet cli."