patch 9.1.0747: various typos in repo found

Problem:  various typos in repo found
Solution: Fix typos (zeertzjq)

closes: #15749

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_listdict.vim b/src/testdir/test_listdict.vim
index 48217cf..f3bdcd4 100644
--- a/src/testdir/test_listdict.vim
+++ b/src/testdir/test_listdict.vim
@@ -1621,7 +1621,7 @@
 
 " Test for using id()
 def Test_id_with_dict()
-  # demonstate a way that "id(item)" differs from "string(item)"
+  # demonstrate a way that "id(item)" differs from "string(item)"
   var d1 = {one: 1}
   var d2 = {one: 1}
   var d3 = {one: 1}