Fixes typo.

Fixes tense of verb.

Author: cldershem

src/12-bluetooth-setup/loopback.md

@@ -1,6 +1,6 @@
 # Loopback, again
 
-After pairing your laptop to the Bluetooth module, your OS should have create a
+After pairing your laptop to the Bluetooth module, your OS should have created a
 device file / COM port for you. On Linux, it should be `/dev/rfcomm*`; on mac,
 it should be `/dev/cu.*` and on Windows, it should be a new COM port.