HPCC-11410 DOCS:Clarify User Security module

Fix HPCC-11410 DOCS:Clarify User Security module
Clarify a section in the Clarify User Security xml module
used by the Installing and Running HPCC document.

Signed-off-by: g-pan <greg.panagiotatos@lexisnexis.com>
Merge pull request #5857 from g-pan/H11410-USect

HPCC-11410 DOCS:Clarify User Security module

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>