doc regex: Avoid confusion in relationship with ECMAScript
doc regex: Avoid confusion in relationship with ECMAScript

The prologue led some users to believe the implementation was compliant with ECMAScript let alone some differences (who *are* documented at the end of the page).
casimir/kakoune,mawww/kakoune,mawww/kakoune,jkonecny12/kakoune,casimir/kakoune,casimir/kakoune,jkonecny12/kakoune,jkonecny12/kakoune,mawww/kakoune,casimir/kakoune,jkonecny12/kakoune,mawww/kakoune