Rename language section: Others -> Other

https://bugzilla.gnome.org/show_bug.cgi?id=620700
Rename language section: Scripts -> Script

https://bugzilla.gnome.org/show_bug.cgi?id=620700
Rename language section: Sources -> Source

https://bugzilla.gnome.org/show_bug.cgi?id=620700
Doc: singular language section names

https://bugzilla.gnome.org/show_bug.cgi?id=620700