First phase of migrating the wiki to the internal docs #11078
rust_version.html is a HTML_DEPS and every html has it as dependecy
auto merge of #11123 : alan-andrade/rust/move_wiki_to_internal_docs, r=brson

This is not done yet but I'm posting it to get feedback.

The wiki has a ton of different tutorials/manuals/faq and so forth. Instead of migrating all of them right now, I just migrated the following:

* The general main wiki page
* Language FAQ
* Project FAQ

If this feels reasonable, please comment so that I can continue with confidence.