better help text on invalid commands

adding help again is a bad idea. code should never
document itself; that's what documentation is for.

so, make the code do a better job telling the user
where to find documentation.

Signed-off-by: Leah Rowe <leah@libreboot.org>

script/roms

@@ -69,7 +69,7 @@ main()
 
 handle_serprog()
 {
-	[ -z "${1+x}" ] && $err "bad command. Check $projectname docs."
+	[ -z "${1+x}" ] && badcmd
 	[ "$1" != "rp2040" ] && [ "$1" != "stm32" ] && $err "bad command"
 	if [ "$1" = "rp2040" ]; then
 		serprog_boards_dir="$picosdk/src/boards/include/boards"

script/trees

@@ -27,7 +27,7 @@ main()
 		-s) mode="savedefconfig" ;;
 		-l) mode="olddefconfig" ;;
 		-n) mode="nconfig" ;;
-		*) $err "Invalid option" ;;
+		*) badcmd "invalid option '-$option'" ;;
 		esac
 		shift; project="${OPTARG#src/}"; shift
 	done