patch 9.0.2135: No test for mode() when executing Ex commands

Problem:  No test for mode() when executing Ex commands
Solution: Add some test cases and simplify several other test cases.
          Also add a few more test cases for ModeChanged.

closes: #13588

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index f7cc8f8..a4a0978 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -6413,9 +6413,9 @@
 		   Rvx	    Virtual Replace mode |i_CTRL-X| completion
 		   c	    Command-line editing
 		   ct	    Command-line editing via Terminal-Job mode
-		   cr	    Command-line while in overstrike mode |c_<Insert>|
+		   cr	    Command-line editing overstrike mode |c_<Insert>|
 		   cv	    Vim Ex mode |gQ|
-		   cvr	    Vim Ex while in overstrike mode |c_<Insert>|
+		   cvr	    Vim Ex mode while in overstrike mode |c_<Insert>|
 		   ce	    Normal Ex mode |Q|
 		   r	    Hit-enter prompt
 		   rm	    The -- more -- prompt