fix: link in README (#9)

Author: hadrien

README.md

@@ -8,8 +8,7 @@ SqlAlchemy integration for FastAPI®
 * Configure environ variables:
   The keys of interest in `os.environ` are prefixed with `sqlalchemy_`.
   Each matching key (after the prefix is stripped) is treated as though it were the
-  corresponding keyword argument to [`sqlalchemy.create_engine`]
-  (https://docs.sqlalchemy.org/en/13/core/engines.html?highlight=create_engine#sqlalchemy.create_engine)  # noqa
+  corresponding keyword argument to [`sqlalchemy.create_engine`](https://docs.sqlalchemy.org/en/13/core/engines.html?highlight=create_engine#sqlalchemy.create_engine)  # noqa
   call.
 
   The only required key is `sqlalchemy_url`, which provides the database URL.