Docs: move option naming to howto-contribute.txt

Docs: move option naming to howto-contribute.txt

Creating and naming options is not done when writing usage().
A contributor may not even read howto-usage-function.txt, but
they should read howto-contribute.txt. So move option naming
and change information there.

Signed-off-by: J William Piggott <elseifthen@gmx.com>