[Tails-project] Sponsorship to attend events on behalf of Ta…

Hi,

it's taken a while but it's finally there! We now have documentation
about how active Tails contributors can get sponsored to attend events
on behalf of Tails:

https://tails.boum.org/contribute/sponsorship_to_attend_events/

If anything is unclear or feels wrong, let's talk about it :)

Cheers,
--
intrigeri