Update docs to v2 (#278)

* Update docs to v2

* Bump checkout action to v3

* Update installer scripts

* Replace v2 to vX on the docs, minor fixes

* Remove extra whitespace

.github/workflows/test-dotnet.yml

@@ -21,7 +21,7 @@ jobs:
         dotnet-version: ['2.1', '2.2', '3.0', '3.1', '5.0']
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Clear toolcache
         shell: pwsh
         run: __tests__/clear-toolcache.ps1 ${{ runner.os }}