Fix markdown linting - add trailing newline

Author: hasbiyallah01

docs/core/tools/dotnet-build.md

@@ -206,4 +206,4 @@ Running `dotnet build` is equivalent to running `dotnet msbuild -restore`; howev
 
   ```dotnetcli
   dotnet build -p:Version=1.2.3.4
-  ```
+  ```