Improve translation instructions (#532)
Improve translation instructions (#532)

* Remove spanish-specific section of CONTRIBUTING.md

* Detail how to add new languages on CONTRIBUTING.md
jdm-contrib/justdelete.me,tupaschoal/justdelete.me,jdm-contrib/justdelete.me,tupaschoal/justdelete.me,jdm-contrib/justdelete.me,tupaschoal/justdelete.me,jdm-contrib/justdelete.me,tupaschoal/justdelete.me