adding documentation

[ahmedhindawi]

• documenting server endpoints
• adding database schema

[mhmadalaa]

The problem now is that we need more clarifications from ML about exactly what they need to store or suppose to be retrieved from API and preprocessed by them.

[ahmedhindawi]

@mhmadalaa 👏🏻💯

[mhmadalaa]

I think we are done for this phase for document things.
The rest is the review for mistakes or modifications and then we will be able to merge.
@Nayra000 @lilhind