api-parse-options.txt: Introduce documentation for parse options API
api-parse-options.txt: Introduce documentation for parse options API

Add some documentation of basics, macros and callback
implementation of the parse-options API.

Signed-off-by: Stephan Beyer <91ae524ae0f8ec8b44ccc7474652ac48e9556db7@gmx.net>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git