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/window.c b/src/window.c
index b2c90c7..db907f8 100644
--- a/src/window.c
+++ b/src/window.c
@@ -4609,7 +4609,7 @@
  * Otherwise put it just before tab page "after".
  *
  * Does not trigger WinNewPre, since the window structures
- * are not completly setup yet and could cause dereferencing
+ * are not completely setup yet and could cause dereferencing
  * NULL pointers
  *
  * Return FAIL or OK.