Added better instructions on SVN sync for dealing with tags/branches.  The previous instructions led to trying to sync *all* branches in the SVN history which is overkill.
Added better instructions on SVN sync for dealing with tags/branches.  The previous instructions led to trying to sync *all* branches in the SVN history which is overkill.

git-svn-id: 5305e2c1a78737cf7dd5f8f44e9bbbd00348fde7@2127 ed100bfc-0583-0410-97f2-c26b58777a21

embray/PyFITS,embray/PyFITS,embray/PyFITS,embray/PyFITS,spacetelescope/PyFITS,spacetelescope/PyFITS