Is there a tutorial for sending data from Thingworx to an edge device using REST?

What exactly are you trying to do with the REST? Call services/update properties?

Generally there are quite a few blog posts/documents on the community regarding the Pi (please use the search bar at the top to utilize) as well as the whole Edge helpcenter:

PTC

DO NOT READ THIS: Installing ThingWorx on a Raspberry Pi

Just to add here there's a blog covering setting up C SDK and sending data from RaspberryPi to ThingWorx Using the C SDK to Deliver Data to ThingWorx from a Raspberry PI

Sorry, I am looking for an example in which Thingworx is able to control an edge device by means of RESTful communication.

To set up bi-directional communication , you need to use Thingworx edge sdks , I have used Java SDK and its achievable through web socket connection.