feat: added Swagger documentation for API routes

[saltykheera]

Added comprehensive api routes
NOTE : the changes made are isolated to the buisness logic of the API
Manually tested the api doc with sample test data from dgp

SAMPLE INPUT:

{
  "projectName":"Aam Digital",
  "projectUrl":"https://github.com/Aam-Digital/ndb-core",
  "projectDescription":"Easy-to-use case management software for the social 
   sector that improves effectiveness and transparency of beneficiary work. 
   Offline-first web app tailored for NGOs worldwide."
}

SAMPLE OUTPUT:

{
  "predictions": [
    {
      "prediction": 0.487,
      "sdg": "SDG 1: No Poverty"
    },
    {
      "prediction": 0.414,
      "sdg": "SDG 2: Zero Hunger"
    },
    {
      "prediction": 0.411,
      "sdg": "SDG 10: Reduced Inequalities"
    }
  ],
  "projectName": "Aam Digital",
  "projectUrl": "https://github.com/Aam-Digital/ndb-core"
}

[saltykheera]

@david-lippert this PR might come in handy for new contributer