HPCC-10496 Document STD.Str.Repeat

Signed-off-by: JamesDeFabia <James.Defabia@LexisNexis.com>
Merge pull request #5476 from JamesDeFabia/10496_Document_Std.Str.Repeat

HPCC-10496 Document STD.Str.Repeat

Reviewed-By: Jamie Noss <james.noss@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>