patch 8.1.0695: internal error when using :popup

Problem:    Internal error when using :popup.
Solution:   When a menu only exists in Terminal mode give an error. (Naruhiko
            Nishino, closes #3765)
diff --git a/runtime/doc/gui.txt b/runtime/doc/gui.txt
index 565f8a5..5df8f53 100644
--- a/runtime/doc/gui.txt
+++ b/runtime/doc/gui.txt
@@ -1,4 +1,4 @@
-*gui.txt*       For Vim version 8.1.  Last change: 2018 Mar 06
+*gui.txt*       For Vim version 8.1.  Last change: 2019 Jan 06
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -914,7 +914,9 @@
 To remove all menus use:			*:unmenu-all*  >
 	:unmenu *	" remove all menus in Normal and visual mode
 	:unmenu! *	" remove all menus in Insert and Command-line mode
-	:aunmenu *	" remove all menus in all modes
+	:aunmenu *	" remove all menus in all modes, except for Terminal
+			" mode
+	:tlunmenu *	" remove all menus in Terminal mode
 
 If you want to get rid of the menu bar: >
 	:set guioptions-=m