Clarifications to FAQ & contributing guidelines

[hauten]

• Updated a few references to specific questions so they are now linked to the appropriate accordions
• Clarified the accordion about not just updating but also using the category tags (it didn't seem clear how to tag your repo to get it into the catalog)
• Emphasized the things you can do to include your repo: organization, logo, tags/catalog

I'm starting to not like two pages for all of these questions/answers, even though Contrib Guidelines was my creation. Jumping back and forth between pages to answer related questions is weird. I may decide to combine everything into the FAQ page, but would need clear headings to separate GitHub questions from catalog questions...