MFC: Document S_IRWXU and permission bits for group/other.
MFC: Document S_IRWXU and permission bits for group/other.

PR:		docs/57153
Approved by:	re (hrs)

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase