HPCC-10289 Document JSONP support

Signed-off-by: JamesDeFabia <James.Defabia@LexisNexis.com>
HPCC-10289 Edits based upon code review

Signed-off-by: JamesDeFabia <James.Defabia@LexisNexis.com>
Merge pull request #5747 from JamesDeFabia/10289_jsonpDocs

HPCC-10289 Document JSONP support

Reviewed-By: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>