patch 8.1.0218: cannot add matches to another window

Problem:    Cannot add matches to another window. (Qiming Zhao)
Solution:   Add the "window" argument to matchadd() and matchaddpos().
            (closes #3260)
diff --git a/src/version.c b/src/version.c
index dd9e1d4..cf7fa29 100644
--- a/src/version.c
+++ b/src/version.c
@@ -799,6 +799,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    218,
+/**/
     217,
 /**/
     216,