Fixed some libraries metadata.

cmaglie · cmaglie · commit 5b4760b88f99 · 2015-01-16T12:22:24.000+01:00
diff --git a/library.properties b/library.properties
@@ -4,5 +4,6 @@ author=Arduino
 maintainer=Arduino <info@arduino.cc>
 sentence=Enables easy access to the motors of the Arduino Robot Motor board. For Arduino Robot only.
 paragraph=
+category=Device Control
 url=http://arduino.cc/en/Reference/RobotLibrary
 architectures=avr
