vim-patch:8.1.1875: cannot get size and position of the popup menu

Problem:    Cannot get size and position of the popup menu.
Solution:   Add pum_getpos(). (Ben Jackson, closes vim/vim#4827)
vim/vim@e9bd572

neovim#11562 backported the vim patch.
This patch only updates the runtime/doc/ files to match Vim.

runtime/doc/autocmd.txt

@@ -583,13 +583,6 @@ ColorSchemePre			Before loading a color scheme. |:colorscheme|
 				Useful to setup removing things added by a
 				color scheme, before another one is loaded.
 
-							*CompleteDone*
-CompleteDone			After Insert mode completion is done.  Either
-				when something was completed or abandoning
-				completion. |ins-completion|
-				The |v:completed_item| variable contains the
-				completed item.
-
 CompleteChanged 					*CompleteChanged*
 				After each time the Insert mode completion
 				menu changed.  Not fired on popup menu hide,
@@ -610,6 +603,13 @@ CompleteChanged 					*CompleteChanged*
   				The size and position of the popup are also
  				available by calling |pum_getpos()|.
 
+							*CompleteDone*
+CompleteDone			After Insert mode completion is done.  Either
+				when something was completed or abandoning
+				completion. |ins-completion|
+				The |v:completed_item| variable contains the
+				completed item.
+
 							*CursorHold*
 CursorHold			When the user doesn't press a key for the time
 				specified with 'updatetime'.  Not re-triggered

runtime/doc/eval.txt

@@ -3121,8 +3121,9 @@ complete_info([{what}])
 		the items listed in {what} are returned.  Unsupported items in
 		{what} are silently ignored.
 
-		To get the position of the popup menu, see |pum_getpos()|. It's
- 		also available in |v:event| during the |CompleteChanged| event.
+		To get the position and size of the popup menu, see
+		|pum_getpos()|. It's also available in |v:event| during the
+		|CompleteChanged| event.
 
 		Examples: >
 			" Get all items