patch 8.1.1586: error number used in two places

Problem:    Error number used in two places.
Solution:   Renumber one. (Ken Takata)

runtime/doc/popup.txt

@@ -483,7 +483,7 @@ The second argument of |popup_create()| is a dictionary with options:
 			tab page.
 			Otherwise the number of the tab page the popup is
 			displayed on; when invalid the popup is not created
-			and an error is given. *E996*
+			and an error is given. *E997*
 	title		Text to be displayed above the first item in the
 			popup, on top of any border.  If there is no top
 			border one line of padding is added to put the title

src/popupwin.c

@@ -892,7 +892,7 @@ popup_create(typval_T *argvars, typval_T *rettv, create_type_T type)
 	tp = find_tabpage(tabnr);
 	if (tp == NULL)
 	{
-	    semsg(_("E996: Tabpage not found: %d"), tabnr);
+	    semsg(_("E997: Tabpage not found: %d"), tabnr);
 	    return NULL;
 	}
     }

src/version.c

@@ -777,6 +777,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1586,
 /**/
     1585,
 /**/