update drone.yml

drone.yml

     - rm -rf $CONTENT
     - ls -la release ; 
       find release -type f -exec md5sum '{}' \;
-    - echo '<<<<<<<{ BUILD FINISHED }>>>>>>>"
+    - echo "<<<<<<<{ BUILD FINISHED }>>>>>>>"
 
 
 # http://plugins.drone.io/drone-plugins/drone-gpgsign/