Update revisions.txt

Author: Federico Fissore

build/shared/revisions.txt

@@ -19,6 +19,7 @@ ARDUINO 1.6.6
 * Examples of libraries with a .development flag file in their root folder won't get marked as read-only. See #2619
 * Update notifications: when updates are available from either Library or Boards Managers, a popup will be shown
 * Introducing arduino-builder, a command line tool that properly calls gcc. Fixes lots of issues about buggy preprocessing.
+* Each open sketch gets built in its own folder, allowing the IDE to recycle previous compilations and being much faster
 
 [libraries]
 * Bridge: YunClient.connected() returns true if there are bytes available for read. Thanks @RobAtticus