[CentOS-docs] Structure for Contribution Pages

[Alain Reguera Delgado]

Hi Guys,

While updating es/ pages, noted that actually there are two Contribute
pages. One in Contribute and other in HowToContribute.

I wonder if we could reorganize that a bit. Maybe separate
contribution needs by SIGs. Then create a Contribution index page
where all those SIG's contribution pages be linked from ? It may be
needed to create some SIGs in those areas where they don't exist.

At this moment (and at least for me) it is a bit confusing to have two
pages for the same thing.

Cheers,
al.