topic_name not covered in docs

[mwkaufman]

It looks like during the below change to asynchronous API, docs/pages/* weren't updated to cover a new required parameter in config.json for all the playbooks. d07b202

Relatedly one might consider the architecture diagram out of date based on this change.

[oleksii-dowjones]

Thanks for pointing this out. We will update documentation soon.

[vigneswararaomacharla]

Updated documentation with topic details.