[DOCS] Update contributing, add changlog

CHANGELOG

-0.2.5 First productive Release
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+# Changelog
+
+| Version | Release    | Type  | Description                             |
+| ------- | ---------- | ----- | --------------------------------------- |
+| 0.1.0   | 15.03.2019 | Major | Alpha version                           |
+| 0.2.5   | 19.03.2019 | Major | Beta version / first productive release |

CONTRIBUTING.md

 # Contribution 
 
+## Information about contributing to this extenstion
+
 Your contribution is welcome. Feel free to create issues. You can also create a 
 merge request. Please note, that we only review merge request
+
+
+### Create Issues
+
+* If you find something missing or something is wrong in this extension,
+  you are welcome to write an issue at https://git-t3o.typo3.org/t3o/election/issues/new  that is describing the problem.
+* If you can, please try to fix the problem yourself and create a merge reuest in this project (you need request group access first)
+* For every change, it is necessary to create an issue first.
+
+
+### Get help
+
+* If you need help with contributing to this extension or If you want to get a maintainer of the extension, please contact: stefan.busemann@typo3.org
+
+
+### requirments for merge requests
+
 * if the coding guidelines are fullfilled
 * acceptance criterias are described
 * unit tests are running
 
-If you want to get a maintainer of the extension, please contact:
-stefan.busemann@typo3.org
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+