Update CONTRIBUTING.md
Update CONTRIBUTING.md

Removed details of how to contribute and replaced with link to generic set of instructions for easier maintenance in future.
TonyRS/ci.maven,patricktiu/ci.maven,samolisov/ci.maven,samolisov/ci.maven,TonyRS/ci.maven,jzinedine/ci.maven,jzinedine/ci.maven,WASdev/ci.maven,patricktiu/ci.maven,WASdev/ci.maven,NottyCode/ci.maven,MisaelSalcido/ci.maven,NottyCode/ci.maven,jgawor/ci.maven,MisaelSalcido/ci.maven,jgawor/ci.maven