add missing volume

Dockerfile

@@ -52,4 +52,5 @@ RUN chmod +x -- /etc/service/*/run /etc/service/*/log/run
 
 ENTRYPOINT ["/sbin/runit-docker"]
 VOLUME ["/var/log/fakeapp1", \
-        "/var/log/fakeapp2"]
+        "/var/log/fakeapp2", \
+        "/var/log/fakeapp3"]