patch 8.2.4107: script context not restored after using <ScriptCmd>

Problem:    Script context not restored after using <ScriptCmd>.
Solution:   Also restore context when not in a script. (closes #9536)
            Add the 'c' flag to feedkeys() to be able to test this.
diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index 2605f6d..9029685 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -2394,6 +2394,9 @@
 			Note that if you manage to call feedkeys() while
 			executing commands, thus calling it recursively, then
 			all typeahead will be consumed by the last call.
+		'c'	Remove any script context when executing, so that
+			legacy script syntax applies, "s:var" does not work,
+			etc.
 		'!'	When used with 'x' will not end Insert mode. Can be
 			used in a test when a timer is set to exit Insert mode
 			a little later.  Useful for testing CursorHoldI.