Make notes how to make a release

+semver:patch

Author: hazzik

ReleaseProcedure.md

@@ -0,0 +1,19 @@
+## How to release
+
+### Ensure tokens are current
+
+Ensure that GitHub and NuGet tokens are not expired. If they are update `GITHUB_TOKEN` and `NUGET_API_KEY` environment variables in AppVeyor.
+
+### Prepare milestone
+
+1. Create milestone
+2. Assign issues to the milestone
+3. Label issues
+4. Create release notes
+    ```ps
+    .\build.ps1 --target Release-Notes
+    ```
+
+### Tag a release
+
+1. Tag the version and push tag to the upstream