Q:

How to add a contributor to your git project?

How do I add a contributor to my public repository on github.com? I tried to find it in the settings menu on github.com, but there is just the possibility of adding collaborators. If I understand the difference between contributor and collaborator correctly I need to add a contributor.

A:

You don't explicitly add contributors.  
A contributor is merely someone whose commits you have incorporated into your git tree.  The presence of their commits in the commit history makes them a contributor ... by definition.
So, for example, the act of accepting someone's pull requests will make them a contributor.

