docs: Add missing symbols to sections.txt
docs: Add missing symbols to sections.txt

https://bugzilla.gnome.org/show_bug.cgi?id=751980

rvu95/vte,rvu95/vte,saitoha/vte-sixel,saitoha/vte-sixel,rvu95/vte,thestinger/vte-ng,saitoha/vte-sixel,rvu95/vte,thestinger/vte-ng,thestinger/vte-ng