Create Backend Wiki documentation

[Denijar]

Developer Story As a developer, I want clear documentation on the structure of the backend, including routes and database schema

Acceptance Criteria

• Database schema updated and put in wiki
• API endpoint table updated, cleaned up, and put in wiki

Additional Context https://drive.google.com/drive/u/2/folders/1AmnqRcr9WySRFszOOXrkCQtSWwPPh-PM