[Milestone] Fix documentation of UCI

[chinmoy12c]

This is a part of UCI milestones: samagra-comms/uci-apis#159

These are the tickets related to this milestone:

• [Docs] Change URLs specified in the docs #40
• [Docs] Update Setting up first conversation according to v2 #34
• [Docs] Update Firebase Notification Adapter documentation to reflect v2 changes. #35
• [Docs] Update documentation of bot setup api to match v2 #36
• [Docs] Update documentation of bot history api to match v2 #37
• [Docs] Documentation update needed in Direct message API. #38
• [Docs] Change url of save credentials in vault #39
• [Docs] Change URLs specified in the docs #40
• [Docs] Change latest branch on inbound setup #41
• [Docs] Settings up conversation Sample Excel Form URL not working #42
• [Docs] Firebase deatails of UCI link in Firebase Notification Adapter not working #43
• Modify Admin Console Manual #52
• Add message flow diagram #51