Merge pull request docker#2239 from londoncalling/compose-startup-order-waitforit

clarified scripts logic for compose startup order

Author: londoncalling

compose/startup-order.md

@@ -47,6 +47,8 @@ script:
           db:
             image: postgres
 
+    >**Tip:** There are limitations to this first solution; e.g., it doesn't verify when a specific service is really ready. If you add more arguments to the command, you'll need to use the `bash shift` command with a loop, as shown in the next example.
+
 -   Alternatively, write your own wrapper script to perform a more application-specific health
     check. For example, you might want to wait until Postgres is definitely
     ready to accept commands: