mdp: clarify about font color `--invert`
mdp: clarify about font color `--invert`

kuanyui/tldr,UncommonPleb/tldr,UncommonPleb/tldr,deekim/tldr,Phizho/tldr,felixonmars/tldr,felixonmars/tldr,zoisom/tldr,AgamAgarwal/tldr,cptdeka10/tldr,UncommonPleb/tldr,zoisom/tldr,slash3b/tldr,katekyan/tldr,cptdeka10/tldr,Phizho/tldr,katekyan/tldr,slash3b/tldr,katekyan/tldr,WALL-E/tldr,Phizho/tldr,kuanyui/tldr,deekim/tldr,cptdeka10/tldr,deekim/tldr,zoisom/tldr,AgamAgarwal/tldr,WALL-E/tldr,slash3b/tldr,felixonmars/tldr