This document lists Tigerbrew and Linuxbrew as interesting forks, not
branches (they used to be "Interesting Branches (aka forks)" but that
changed in b745546), so "Interesting Taps & Branches" is a more fitting
title.
The term "branches" is also presumably confusing to folks with a shallow
understanding of GitHub and/or git who may not realize how GitHub forks
and git branches are related.
Remove duplication, link to the API documentation more often,
tweak wording, add `@UniqMartin` as a maintainer, note `@jacknagel`'s
and `@adamv`'s significant past contributions to Homebrew, delete some
outdated or unneeded documentation, add some missing `Formula` API.
entries and simplify/improve `CONTRIBUTING.md`.
ClosesHomebrew/homebrew#46179.
ClosesHomebrew/homebrew#46618.
Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
