add hint to a simple way to deal with missing license files
add hint to a simple way to deal with missing license files

(issue #1071)

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