move FAQ pages into one page

[jum-s]

today's workflow : "create a page, create its links in the faq summary page, ask for its translation."
proposition: "editing an existing page which would gather all faq questions"

to consider :

• Summaries a automatic now (easy linking within the page)
• Anchors can still link a question from elsewhere
• Whenever i arrive on a faq, every question are gathered into one page

[maxlath]

When we were on jingo, having all FAQ on one page would have made translation a pain as there was no sections; but now that we have translation per paragraph, I guess having all FAQ on a single page would indeed be an improvement. Old 1-Q/A pages can then be turned into redirects to the corresponding anchor