changelog: update for v2.0
changelog: update for v2.0

rgrinberg/merlin,ocaml/merlin,haselwarter/merlin,ocaml/merlin,haselwarter/merlin,fxfactorial/merlin,chriskonstad/merlin,rgrinberg/merlin,chambart/merlin,dra27/merlin,fxfactorial/merlin,haselwarter/merlin,rgrinberg/merlin,ocaml/merlin,chambart/merlin,haselwarter/merlin,dra27/merlin,neojski/merlin,neojski/merlin,the-lambda-church/merlin,fxfactorial/merlin,chambart/merlin,dra27/merlin,the-lambda-church/merlin,neojski/merlin,chambart/merlin,the-lambda-church/merlin,ocaml/merlin,fxfactorial/merlin,dra27/merlin,chriskonstad/merlin,rgrinberg/merlin,neojski/merlin