README: improved the section on emacs.
README: improved the section on emacs.

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