doc(keys): mention punctuation text-objects
doc(keys): mention punctuation text-objects

The fact that punctuation characters can act as surrounding
delimiters is a useful behavior but not obvious.

This "hidden" text-object feature deserves to be described explicitely.

mawww/kakoune,jkonecny12/kakoune,Somasis/kakoune,danr/kakoune,danr/kakoune,casimir/kakoune,danr/kakoune,alexherbo2/kakoune,Somasis/kakoune,mawww/kakoune,casimir/kakoune,casimir/kakoune,mawww/kakoune,casimir/kakoune,jkonecny12/kakoune,jkonecny12/kakoune,Somasis/kakoune,lenormf/kakoune,alexherbo2/kakoune,mawww/kakoune,danr/kakoune,jkonecny12/kakoune,alexherbo2/kakoune,lenormf/kakoune,Somasis/kakoune,alexherbo2/kakoune,lenormf/kakoune,lenormf/kakoune