Explicitly say that this is an internal library which is intended to be used within FreeBSD base system only, and discourage user applications from using it.  User applications should use the expat version from the ports/package collection.
Explicitly say that this is an internal library which is intended to be
used within FreeBSD base system only, and discourage user applications
from using it.  User applications should use the expat version from the
ports/package collection.

Reviewed by:	simon (earlier version)

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