Update and rename ReadMe.md to README.md

Author: meganrobinson22

projects/ultrasonic_rvr/README.md

@@ -0,0 +1,4 @@
+# Ultrasonic RVR
+You can find the tutorial for this demo [here].
+
+[here]: https://sdk.sphero.com/docs/samples_content/raspberry_pi/python/ultrasonic_rvr_sample/