HPCC-10004 DOCS:XREF Warning

Fix HPCC-10004 DOCS:XREF Warning
Provide Warning about allowing
all users access to XREF.

Signed-off-by: g-pan <greg.panagiotatos@lexisnexis.com>
Merge pull request #4995 from g-pan/H10004XrefInst

HPCC-10004 DOCS:XREF Warning

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>