patch 9.1.0936: cannot highlight completed text

Problem:  cannot highlight completed text
Solution: (optionally) highlight auto-completed text using the
          ComplMatchIns highlight group (glepnir)

closes: #16173

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/version9.txt b/runtime/doc/version9.txt
index bcda3d0..8993e3c 100644
--- a/runtime/doc/version9.txt
+++ b/runtime/doc/version9.txt
@@ -41653,6 +41653,7 @@
 
 Highlighting: ~
 
+|hl-ComplMatchIns|	matched text of the currently inserted completion.
 |hl-MsgArea|		highlighting of the Command-line and messages area
 |hl-PmenuMatch|		Popup menu: highlighting of matched text
 |hl-PmenuMatchSel|	Popup menu: highlighting of matched text in selected