docs: info on using sqlalchemy Session objects

README.md

@@ -126,25 +126,41 @@ split_features = split_by_sql(
 
 - The db parameter can be a connection string to start a new connection.
 - Or an existing database connection can be reused.
-- To do this, the psycopg2 driver connection needs to be passed:
+- To do this, either the psycopg2 connection, or a SQLAlchemy Session
+  must be passed:
 
 SQLAlchemy example:
 
 ```python
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
+from fmtm_splitter.splitter import split_by_sql
 
 # Creates a SQLAlchemy Session object
 engine = create_engine("postgresql://postgres:postgres@localhost/postgres")
 SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
 db = SessionLocal()
 
-psycopg2_connection = db.connection()
-
 # Then pass this object as the db param
 split_features = split_by_sql(
     aoi,
-    psycopg2_connection,
+    db,
+    num_buildings=50,
+    osm_extract=osm_extracts,
+)
+```
+
+psycopg2 example:
+
+```python
+import psycopg2
+from fmtm_splitter.splitter import split_by_sql
+
+db = psycopg2.connect("postgresql://postgres:postgres@localhost/postgres")
+
+split_features = split_by_sql(
+    aoi,
+    db,
     num_buildings=50,
     osm_extract=osm_extracts,
 )