patch 8.1.2238: error in docs tags goes unnoticed

Problem:    Error in docs tags goes unnoticed.
Solution:   Adjust tags build command. (Ken Takata, closes #5158)
diff --git a/src/version.c b/src/version.c
index 3eaf21f..e1d5c64 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2238,
+/**/
     2237,
 /**/
     2236,