Add docs for pulling and setting up postman collection of BE endpoints

[jperk51]

ACs:

• Investigate possibility of auto generating postman collection from new api docs json
• Create walkthrough docs for setting up postman collection and hitting endpoints in staging

[kpethtel]

Here's the current postman collection: modules/mobile/docs/MobileAPI Integration Test Collection.postman_collection.json

[Tonksthebear]

Updated the collection and docs. Automated postman updates would be possible, but would require some finesse to handle endpoints with extra parameters