[OPEN-ILS-DOCUMENTATION] Patch for SIP Server documentation

[Dan Scott]

The attached patch, against the rel_2_0 branch, points users to the
correct current SIPServer git repository and removes references to the
out of date git and CVS repositories. It also uses an approach for
adding a new group that does not depend on a specific database ID, and
fixes a couple of minor typos.

I couldn't find the equivalent documentation in master or rel_2_1 but
the instructions should be identical, so I'd advise getting the file
into place.