Bugfix update for transfer of company data from mongo to sql (#121)

Fixed the following errors:

- Typo in readme.md
- Mongo delivers the last_update of an company as a string not as date.

Added:
- Entrypoint description in readme.md

tests/utils/data_transfer_test.py

@@ -262,7 +262,7 @@ def company_generator(seed: int) -> dict[str, Any]:
             "zip_code": get_random_zip() if random.choice([True, False]) else None,
             "street": get_random_string(20) if random.choice([True, False]) else None,
         },
-        "last_update": date(random.randint(2000, 2023), 1, 1),
+        "last_update": date(random.randint(2000, 2023), 1, 1).isoformat(),
     }