Phpmyadmin: Improve CONTRIBUTING.md file

[mauriciofauth]

The CONTRIBUTING.md file needs to be improved to include more information about the phpMyAdmin workflow. This can be done either by adding information in the file itself or by indicating where to get more details about that particular information.

Some information about the workflow can be found on the phpMyAdmin wiki and in the contribute section on the website.

Developer_guidelines wiki page should be a good starting point. Other related wiki pages should also be updated.

CONTRIBUTING.md is primarily targeted to new contributors, so this needs to be taken into account.

[ibennetch]

I think we should consolidate this information into the wiki and provide a brief overview in the contributing file and website, then refer people to the wiki for more detailed information.

Also, for things like creating a pull request, the Github documentation is outstanding and better than anything we could come up with, so while there are many things specific to our project that we will want to include, a lot of the general workflow staff has already been written elsewhere.

[kartik1000]

Also, @ibennetch I feel that if we add a separate documentation explaining a bit about the codebase of phpmyadmin, the twig template that we use and other frameworks which are involved, it will be a good guide for any newcomer and they can immediately start contributing without much chaos. We can also make that as an addition to CONTRIBUTING.md if we wish to keep it brief. I am ready to help wherever needed :)

[ibennetch]

In general, that sort of documentation would be more suited for the wiki. Anyone can edit that and most of our documentation for developers is located there.

Your suggestions are appreciated, though. Thanks for the input.