Documentation Changes

More proposed documentation updates.

Acceptable Formulae:

* Adds Perl to the list of stuff we offer Dupes of in the Core.
* Notes that OS X’s OpenSSL is usually horribly outdated.
* Removes the incorrect space between font and forge.

Common Issues:

* We said three issues, we listed four. Oops.

External Commands:

* The cache is usually at /Library rather than ~/Library, and the rest
of the documentation says /Library, so this makes the referencing
consistent.

FAQ:

* Adds a tiny section on pinning formulae.

Interesting-Taps-And-Branches:
* Notes gaming-emulation software belongs in Homebrew/Games as well.
* nolith/Embedded hasn’t been touched for 28 months. I’ve cut it.
* anarchivist/forensics hasn’t been touched for 35 months. I’ve cut it.
* codebutler’s GTK+ experiment seems to have been terminated after one
commit. I’ve cut it.
* paxam/linux hasn’t been touched for 34 months. I’ve cut it.
* rmyers/homebrew hasn’t been touched in 42 months. I’ve cut it.
* nddrylliog/winbrew has moved, I’ve changed the URL to the new one.

Winbrew.md:
* Removed. It’s referenced in the prior file, and doesn’t really need
its own.

Closes Homebrew/homebrew#34599.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>