Update release notes

Signed-off-by: Sahas Subramanian <[email protected]>

Author: shsms

RELEASE_NOTES.md

@@ -10,6 +10,8 @@
     * Rename `receive_trades` to `receive_public_trades`
     * Rename `receive_orders` to `receive_gridpool_orders`
 
+- The `stream_*` methods in the client have been renamed to `*_stream`.  They no longer return `Receiver` instances, but rather `GrpcStreamBroadcaster` instances.  They expose a `new_receiver()` method which can be used to get a new receiver.  They also expose a `stop()` method which can be used to stop the background streaming task when the stream is no longer needed.
+
 ## New Features
 
 * Print tags and filled (instead of open) quantity for gridpool orders in CLI tool.