Optimizing battery time on Trisquel - wiki docs added

Hi

Following the recent thread on squeezing battery time I summarized the
discussion's resources and some other tips I've found on this wiki page:
https://trisquel.info/en/wiki/optimizing-battery-time

I think the Linux Libre information deserves a separate, dedicated page
with more details on the current PPAs for example. I'll probably get to
it sometime later this month but anyone else is welcome to augment/move
the information on that page as seen fit.

Cheers,

F.

--
Fabián Rodríguez
http://trisquel.magicfab.ca