Adding sBTC docs

[wileyj]

• add link to the governing docs in the FAQ
• add documents around sbtc governance

Initial push/PR of this content, still a lot of formatting to go

[wileyj]

@marthaadrienne these files have the changes from your comments in the .github PR. i'll continue working on them and open this PR or review once that work is done

[wileyj]

Only one recommended adjustment shown in a comment.

Lots of changes since this comment - should be addressed now

[will-corcoran]

this looks great @wileyj thanks for pulling all this together. I just had the one comment on the ascii diagram. other than that - good to go!

[wileyj]

this is being merged - any other changes, please create an issue or PR the change to the master branch