help: only speak of Control and Meta sequences

Don't call the latter ones Escape sequences, because both Control
and Meta sequences can be entered using the Escape key.

src/help.c

@@ -336,14 +336,12 @@ void help_init(void)
 		"the third line from the bottom and shows important "
 		"messages.  ");
 	htx[1] = N_("The bottom two lines show the most commonly used "
-		"shortcuts in the editor.\n\n The notation for "
-		"shortcuts is as follows: Control-key sequences are "
-		"notated with a caret (^) symbol and can be entered "
-		"either by using the Control (Ctrl) key or pressing "
-		"the Escape (Esc) key twice.  Escape-key sequences are "
-		"notated with the Meta (M-) symbol and can be entered "
-		"using either the Esc, Alt, or Meta key depending on "
-		"your keyboard setup.  ");
+		"shortcuts in the editor.\n\n Shortcuts are written as "
+		"follows: Control-key sequences are notated with a '^' "
+		"and can be entered either by using the Ctrl key or "
+		"pressing the Esc key twice.  Meta-key sequences are "
+		"notated with 'M-' and can be entered using either the "
+		"Alt, Cmd, or Esc key, depending on your keyboard setup.  ");
 	htx[2] = N_("Also, pressing Esc twice and then typing a "
 		"three-digit decimal number from 000 to 255 will enter "
 		"the character with the corresponding value.  The "