How seqeulize knows how to connect to our database

config.json

{
  "development": {
    "username": "YOUR-USERNAME",
    "password": "YOUR-PASSWORD",
    "database": "League-Spx",
    "host": "127.0.0.1",
    "dialect": "postgres"
  },
  "test": {
    "username": "YOUR-USERNAME",
    "password": "YOUR-PASSWORD",
    "database": "League-Spx-Test",
    "host": "127.0.0.1",
    "dialect": "postgres"
  },
  "production": {
    "use_env_variable": "DATABASE_URL",
    "database": "League-Spx",
    "dialect": "postgres",
    "dialectOptions": {
      "ssl": {
        "rejectUnauthorized": false
      }
    }
  }
}