Add CONTRIBUTING.md file general structure

CONTRIBUTING.md

+# CONTRIBUTING GUIDELINES
+
+1. [Use the search Luke](#use-the-search-luke)
+2. [You have a problem](#you-have-a-problem)
+3. [You have a solution](#you-have-a-solution)
+
+**BONUS:** [You have spare time to volunteer](#you-have-spare-time-to-volunteer)
+
+
+## USE THE SEARCH LUKE
+
+> May the Force (of past experiences) be with you.
+
+Trust me, that works 90% of the time.
+
+You can also take a look at the [FAQ](https://github.com/robbyrussell/oh-my-zsh/wiki/FAQ)
+to be sure it hasn't already come up.
+
+If all fails, your thing hasn't probably been reported yet, so you can go ahead
+and read on to the next section.
+
+
+## YOU HAVE A PROBLEM
+
+See [point 1](#use-the-search-luke).
+
+If the problem is already reported, comment on the issue so we can know there's
+more people with the problem.
+
+If not, look at the [Troubleshooting](https://github.com/robbyrussell/oh-my-zsh/wiki/Troubleshooting)
+page for instructions on how to gather data to better debug your problem.
+
+Then, you can go ahead and submit an issue with as much detail as you can provide.
+We'll do our very best to help you.
+
+*TODO: fill later*
+
+
+## YOU HAVE A SOLUTION
+
+See [point 1](#use-the-search-luke).
+
+If the solution is already reported, try it out and +1 the pull request if the
+solution works ok. On the other hand, if you think your solution is better, post
+it so we can have both solutions to compare.
+
+If not, then go ahead and submit a PR.
+**Unless your solution is yet another [theme](https://github.com/robbyrussell/oh-my-zsh/wiki/Themes#dont-send-us-your-theme-for-now).**
+
+*TODO: fill later*
+
+
+----
+
+### YOU HAVE SPARE TIME TO VOLUNTEER
+
+Very nice!! :)
+
+Please have a look at the [Volunteer](https://github.com/robbyrussell/oh-my-zsh/wiki/Volunteers)
+page for instructions on where to start and more.