runtime(doc): remove non-existent parameter in shift-command (#13626)

The variant with the {count} parameter is explained in the next item.

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/change.txt b/runtime/doc/change.txt
index dccaa44..7741312 100644
--- a/runtime/doc/change.txt
+++ b/runtime/doc/change.txt
@@ -516,7 +516,7 @@
 			lines to [indent] (default 0).
 
 							*:>*
-:[range]> [flags]	Shift {count} [range] lines one 'shiftwidth' right.
+:[range]> [flags]	Shift [range] lines one 'shiftwidth' right.
 			Repeat '>' for shifting multiple 'shiftwidth's.
 			See |ex-flags| for [flags].