Remove duplicate Contributing.md

CONTRIBUTING.md

@@ -1 +1,4 @@
-To get started, [sign the Contributor License Agreement](https://www.clahub.com/agreements/wekan/wekan).
+To get started, [please sign the Contributor License Agreement](https://www.clahub.com/agreements/wekan/wekan).
+
+[Then, please read documentation at wiki](https://github.com/wekan/wekan/wiki).
+

Contributing.md

@@ -1,5 +0,0 @@
-# Contributing
-
-Please see wiki for all documentation:
-
-<https://github.com/wekan/wekan/wiki>