apparmor: update git and wiki locations in AppArmor docs

The apparmor information in the apparmor.rst file is out of date.
Update it to the correct git reference for the master apparmor tree.
Update the wiki location to use apparmor.net which forwards to the
current wiki location on gitlab.com. Update user space tools address
to gitlab.com.

Signed-off-by: Jordan Glover <Golden_Miller83@protonmail.ch>
Signed-off-by: John Johansen <john.johansen@canonical.com>

doc: ReSTify apparmor.txt

Adjusts for ReST markup and moves under LSM admin guide.

Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>