Changed and added comments in the database files

src/database/change.py

@@ -7,6 +7,7 @@ from . import models
 def change_master_pass(
     engine: Engine, user_id: int, salt: bytes, passwd: bytes
 ) -> None:
+    """Changes master password and salt in the database"""
     statement = (
         sqlmodel.update(models.MasterPass)
         .where(models.MasterPass.user_id == user_id)