patch 9.0.1886: Various Typos

Problem:  Various Typos
Solution: Fix Typos

This is a collection of typo related commits.

closes: #12753
closes: #13016

Co-authored-by: Adri Verhoef <a3@a3.xs4all.nl>
Co-authored-by: zeertzjq <zeertzjq@outlook.com>
Co-authored-by: Viktor Szépe <viktor@szepe.net>
Co-authored-by: nuid64 <lvkuzvesov@proton.me>
Co-authored-by: Meng Xiangzhuo <aumo@foxmail.com>
Co-authored-by: Dominique Pellé <dominique.pelle@gmail.com>

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_highlight.vim b/src/testdir/test_highlight.vim
index 6e39d4e..af60503 100644
--- a/src/testdir/test_highlight.vim
+++ b/src/testdir/test_highlight.vim
@@ -878,7 +878,7 @@
   hi clear
 endfunc
 
-" Test for 'ctermul in a highlight group
+" Test for 'ctermul' in a highlight group
 func Test_highlight_ctermul()
   CheckNotGui
   call assert_notmatch('ctermul=', HighlightArgs('Normal'))