[Nitro] 0.50.0 RELEASES file

[George Moschovitis]

Dear devs,

I have updated the file doc/RELEASES in the repo. I would appreciate if some of you could have a look at this file and the rest of the files in doc, and fix some typo/english errors.

thanks,
-g.

--
http://gmosx.me.gr
http://joy.gr
http://cull.gr
http://nitroproject.org
http://phidz.com
http://joyerz.com