Update CONTRIBUTING.md to point to the How to contribute page
# Contributing to the Enarx project
The Enarx project welcomes contributions!
-Please refer to our [guidelines](https://github.com/enarx/enarx.github.io/blob/master/CONTRIBUTING.md) for information on how to do so.
+Please refer to our [guidelines](https://github.com/enarx/enarx/wiki/How-to-contribute) for information on how to do so.
