Documentation for async (webhook) mode of BAP Client

[vbabuEM]

Problem: A couple of months ago, it was verified by the protocol server team that the BAP-Client Protocol Server instance can be configured in async(webhook) mode where it will not wait for responses for messages, rather call back the webhook when it gets responses. There is no documentation explaining this feature to users.

Solution: Faiz wanted the documentation to be updated with the following information: a. Configuration changes required for the BAP Client PS to be configured in the webhook mode b. Simple sequence diagram showing how search & select messages will work in the webhook mode.

cc @em-abee

[emmayank]

[Proof of Completion] Document link - https://fide-official.atlassian.net/wiki/spaces/BTD/pages/edit-v2/558071822?draftShareId=422413bf-be1d-4dc0-8b2f-7db6d41db6fc

[emmayank]

Hey @vbabuEM , requesting you to please review the document and provide feedback. making you the reviewer of the ticket. please review and publish it if everything is fine.

thanks @em-abee

cc:: @faizmagic

[vbabuEM]

@emmayank , I think I mentioned it to @em-abee . I dont know if it is regarding this topic. Basically the deal is that Confluence pages are tricky to expose to others. The best place for this documentation is the protocol server repository itself. Maybe we can put the document in the docs folder and if you feel necessary, link it from readme or the guide.

[em-abee]

@vbabuEM - We can document in readme file as well. I'll do it.

[em-abee]

PR: https://github.com/beckn/protocol-server/pull/226