docs(dotnet): Fix stupid github workflow versioning

Github ignores subversions if they contain zero. Smart.

.github/workflows/dotnet.yml

@@ -19,7 +19,7 @@ jobs:
         tag:
           - 2.1
           - 3.1
-          - 5.0
+          - 5
     steps:
       - uses: actions/checkout@v2
       - uses: docker/setup-buildx-action@v1

README.md

@@ -43,7 +43,7 @@ is tagged correctly.
   * [`dotnet3.1`](/dotnet/3.1)
     * `ghcr.io/parkervcp/yolks:dotnet_3.1`
   * [`dotnet5.0`](/dotnet/5.0)
-    * `ghcr.io/parkervcp/yolks:dotnet_5.0`        
+    * `ghcr.io/parkervcp/yolks:dotnet_5`        
 ### [Erlang](/erlang)
   * [`erlang22`](/erlang/22)
     * `ghcr.io/parkervcp/yolks:erlang_22`