Update README

Update example with engine parameter.

Signed-off-by: Michal Konecny <[email protected]>

README.rst

@@ -19,11 +19,13 @@ This is an example of database entity diagram generation:
 
 .. code-block:: python
 
- from sqlalchemy import MetaData
+ from sqlalchemy import MetaData, create_engine
  from sqlalchemy_schemadisplay import create_schema_graph
 
  # create the pydot graph object by autoloading all tables via a bound metadata object
- graph = create_schema_graph(metadata=MetaData('postgres://user:pwd@host/database'),
+ graph = create_schema_graph(
+ engine=create_engine('postgresql+psycopg2://user:pwd@host/database'),
+ metadata=MetaData('postgres://user:pwd@host/database'),
  show_datatypes=False, # The image would get nasty big if we'd show the datatypes
  show_indexes=False, # ditto for indexes
  rankdir='LR', # From left to right (instead of top to bottom)