add comments for unbound avoid port configuration

unbound.conf

@@ -8,12 +8,12 @@ server:
     hide-identity: yes
     hide-version: yes
     outgoing-port-permit: 1024-65535
-    outgoing-port-avoid: 3000
-    outgoing-port-avoid: 4000
-    outgoing-port-avoid: 6379
-    outgoing-port-avoid: 7275
-    outgoing-port-avoid: 8008
-    outgoing-port-avoid: 8080
+    outgoing-port-avoid: 3000 # mastodon web
+    outgoing-port-avoid: 4000 # mastodon streaming
+    outgoing-port-avoid: 6379 # redis
+    outgoing-port-avoid: 7275 # supl
+    outgoing-port-avoid: 8008 # synapse
+    outgoing-port-avoid: 8080 # attestation
 
 forward-zone:
     name: "."