Correction to base URL for paper trading.

As is using the primary URL for a paper trading account with fail with a 404.

Author: jwesleye

README.md

@@ -48,9 +48,7 @@ follows.
 ## Base URL
 
 The base URL for API calls defaults to `https://api.alpaca.markets/`. This endpoint
-is for live trading, and for paper trading and other purposes, you can to change
-the base URL. You can pass `base_url` kwarg to `REST()`, or using the environment
-variable, `APCA_API_BASE_URL`.
+is for live trading. You can to change the base URL to 'https://paper-api.alpaca.markets' for paper trading. You can change by passing a url as `base_url` input to `REST()`, or using the environment variable, `APCA_API_BASE_URL` in you env file.
 
 The environment variable `APCA_API_DATA_URL` can also be changed to configure the
 endpoint for returning data from the `/bars` endpoint. By default, it will use