Merge pull request #6990 from Scooletz/master

.NET client introduced to docs

doc/api/README.md

@@ -26,6 +26,7 @@
 + [python-gitlab](https://github.com/Itxaka/python-gitlab) - Python
 + [java-gitlab-api](https://github.com/timols/java-gitlab-api) - Java
 + [node-gitlab](https://github.com/moul/node-gitlab) - Node.js
++ [NGitLab](https://github.com/Scooletz/NGitLab) - .NET
 ## Introduction