Resolve "Update README.md to link to backbone-message-format for topic definition"

Closes #19 (closed)

README.md

 }
 ```
 
-### Topics and Subscriptions 
+### Topics 
 
-The topics have the following structure: 
-
-```
-project.operator.vehicleType.vehicleID.[send|receive].messageType
-# eg 
-soar.noc.autosub.ah1.send.platform-mission 
-# or 
-soar.po.ecosub.eco1.receive.platform-status
-```
-
-Subscriptions may contain single-word wildcards (*) or multi-word wildcards (#).
+When sending messages you should publish them using a topic matching [this definition](https://git.noc.ac.uk/communications-backbone-system/backbone-message-format#topics).
 
 ## Encoding and decoding