Update .asf.yaml with hacktoberfest topic (#2)

diff --git a/.asf.yaml b/.asf.yaml
index 4a121e3..ed1eb86 100644
--- a/.asf.yaml
+++ b/.asf.yaml
@@ -25,6 +25,7 @@
   labels:
     - java
     - classloader
+    - hacktoberfest
   features:
     wiki: false
     issues: true