docs: clarify completeopt

Author: dundargoc

runtime/doc/options.txt

@@ -2152,12 +2152,13 @@ A jump table for the options with a short description can be found at |Q_op|.
 		    {only works when compiled with the |+textprop| feature}
 
 	   noinsert Do not insert any text for a match until the user selects
-		    a match from the menu. Only works in combination with
-		    "menu" or "menuone". No effect if "longest" is present.
+		    a match from the menu. Starts on menu item 1. Only works
+		    in combination with "menu" or "menuone". No effect if
+		    "longest" or "noselect" is present.
 
-	   noselect Do not select a match in the menu, force the user to
-		    select one from the menu. Only works in combination with
-		    "menu" or "menuone".
+	   noselect Do not insert any text for a match until the user selects
+		    a match from the menu. Starts on menu item 0. Only works
+		    in combination with "menu" or "menuone".
 
 	   fuzzy    Enable |fuzzy-matching| for completion candidates. This
 		    allows for more flexible and intuitive matching, where