Add Spanish translation to application

[mariinkys]

Added Spanish translation files.

[hepp3n]

Well done, thank you so much! I'm not sure when it will be on flathub tho, currently working on cosmic applet and we have few bugs to fixing :)

But I will try to push it as fast as possible :)

[mariinkys]

Yeah don't worry. Keep up the great work (:

[hepp3n]

Thanks! :)