Add documentation about how to build queues.

Add a how-to set of documentation about building queues with Asterisk.
This documentation is based on Asterisk 1.6.2 but should work on most
versions with minor modifications.

(closes issue #16237)
Reported by: lmadsen
Patches:
      Building Queues (FINAL).txt uploaded by lmadsen (license 10)
Tested by: pdhales, lmadsen, cmdrwalrus

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@240039 65c4cc65-6c06-0410-ace0-fbb531ad65f3