Feature/184 update swagger documentation

[K-Schubert]

Overview

Added more documentation for swagger docs in Fastapi app().

Changes Made

• Added documentation to app in autocomplete/app/main.py
• Added documentation to app in indexing/app/main.py
• Added documentation to app in rag/app/main.py

Testing

docker-compose up --build and check if API documentation is updated.

Requested Reviewers

@tabee