fix(how_to_user): update status response to be 201
fix(how_to_user): update status response to be 201

The status response from the thumbifier service when creating a new job
is actually `201` and not `200` as the docs and example suggest.

The areas in the documentation have been updated to reflect the correct
status code response.

sysdia-solutions/thumbify_me_website,sysdia-solutions/thumbify_me_website,sysdia-solutions/thumbify_me_website,sysdia-solutions/thumbify_me_website