HPCC-10740 Document how to override default width

Fixes HPCC-10740

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge pull request #21 from GordonSmith/HPCC-10740

HPCC-10740 Document how to override default width

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>