Moved checkout above setup step to align with the other samples (#256)

README.md

@@ -34,9 +34,9 @@ Multiple versions:
 
 ```yml
 steps:
-- name: Setup dotnet
 - uses: actions/checkout@v2
-- uses: actions/setup-dotnet@v1
+- name: Setup dotnet
+  uses: actions/setup-dotnet@v1
   with:
     dotnet-version: | 
       3.1.x