HPCC-11525 Document default quote character

Signed-off-by: JamesDeFabia <James.Defabia@LexisNexis.com>
Merge pull request #6071 from JamesDeFabia/11525Document_default_quote_character

HPCC-11525 Document default quote character

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>