Disable GitHub issues (#570)

diff --git a/.asf.yaml b/.asf.yaml
index 66919a6..7d09281 100644
--- a/.asf.yaml
+++ b/.asf.yaml
@@ -29,7 +29,8 @@
     squash:  true
     merge:   false
     rebase:  false
-
+  features:
+    issues:  false
 notifications:
   commits:      notifications@skywalking.apache.org
   issues:       notifications@skywalking.apache.org