Add top-level sequence diagrams
It would be useful to illustrate information flow via the API with some sequence diagrams. For example:
- Client-side "set" operation
- Server-side "read" operation
- Server-side "observe" operation
Affects 0.1.9.
@TonyWalsworthImg - does this look like what we would need for a sequence diagram for the Client-side "set" operation?

These sequence diagrams could go under the user guide, as an explanation of how the API works? or perhaps in the developer guide as an explanation of the architecture for Awa development?
This looks good – yes. Except that ‘AwaError_Sucess’ should have double c.
Is it worth adding the EstablishNotify message after Connect Request Message? Or maybe that's best left for Subscribe/Observe examples.
Also, you can probably just call it "Connect Request" and "Connect Response" rather than "Connect Request Message", as the word "Message" isn't used anywhere else.