update CHANGELOG to mention the new subcommand
update CHANGELOG to mention the new subcommand

(issue #1630)

moyogo/fontbakery,graphicore/fontbakery,graphicore/fontbakery,graphicore/fontbakery,googlefonts/fontbakery,googlefonts/fontbakery,moyogo/fontbakery,moyogo/fontbakery,googlefonts/fontbakery