[lwip-members] contrib doc

[Jani Monoses]

I can check the doc in and then any of you can review and change it.
will the doc/contrib.txt name do or do you have something more suggestive?
maybe doc/devel.txt and that can have the ocntrib section the maintainers 
section
and possibly a todo section?I like the in -source TODO idea better than 
savannah because
it's a lot easier to work with.TODO as in a complement to savannah bugs more 
like a task
list with ideas for medium-long term.
thoughts?