[GRASS-dev] Added i.landsat8.swlst in grass-addons

[Nikos Alexandris]

Dear all,

I've been asked off-line some times for the custom script available at
https://github.com/NikosAlexandris/i.landsat8.swlst -- specifically on how to
get it installed.

I added this now in GRASS Add-Ons since the easiest way, for new users,
to install one, is to use g.extension.

I hope I didn't do anything wrong in adding this.  Due to lack of time,
I didn't check if all is well.  Please, let me know in case I overlooked
something that might hinder the normal workflow in the addons
repository.

Cheers, Nikos