docs/Formula-Cookbook: several content updates

keg_relocate: Fix Error: wrong number of arguments [Linux]

Fix the error:
Error: wrong number of arguments (given 1, expected 2)
/projects/btl_scratch/sjackman/brew/Homebrew/Library/Homebrew/exceptions.rb:550:in `block in initialize'
/projects/btl_scratch/sjackman/brew/Homebrew/Library/Homebrew/exceptions.rb:559:in `map'

Bump ruby-macho from 2.0.0 to 2.1.0 in /Library/Homebrew/vendor

- update rubydoc.info link URLs to use HTTPS
- link to specific example formula revisions so line highlighting makes sense
- monospace formula link text

And both dependencies and Requirements accept lists.

Add `:fossil`, `:github_private_release`, `:github_private_repo`, `:s3`, `:scp`.

Bumps [ruby-macho](https://github.com/Homebrew/ruby-macho) from 2.0.0 to 2.1.0.
- [Release notes](https://github.com/Homebrew/ruby-macho/releases)
- [Commits](https://github.com/Homebrew/ruby-macho/compare/2.0.0...2.1.0

)

Signed-off-by: dependabot[bot] <support@dependabot.com>

docs/How-To-Open-a-Homebrew-Pull-Request: move sample commands into code blocks

Skip quitting applications when not logged into GUI.

Fix `atomic_write` inside non-sticky directory.

Fix `brew mirror`.

Force `chmod_R` after extracting.

DevelopmentTools::locate: Prefer brewed tools [Linux]

xcode: fix expected Clang version for CLT with Xcode 10 (10A255)

rubocop: move requirement to configuration file

Make all extracted files writable after extracting.

Don’t treat `.7z` as part of a version.