Update cvmfs/catalog_mgr.h
Update cvmfs/catalog_mgr.h

kLookupRawSymlink update description

Co-authored-by: Jakob Blomer <41accfafbf5b91f8f2d77764cb6bdb506cd0b50a@cern.ch>
cvmfs/cvmfs,cvmfs/cvmfs,cvmfs/cvmfs,cvmfs/cvmfs,cvmfs/cvmfs,cvmfs/cvmfs,cvmfs/cvmfs