doc: document the ReactToEvents sample
doc: document the ReactToEvents sample

Change-Id: I978218f10ac577872a277bb4764208b1619b5885
Reviewed-on: http://gerrit.aldebaran.lan/31291
Reviewed-by: cgestes <ddb78fe00abb42f91254c16a0860e38eb0781789@aldebaran-robotics.com>
Reviewed-by: dmerejkowsky <1e4b13000fa8777df4cefd2fd8215187e3deb062@aldebaran-robotics.com>
Tested-by: dmerejkowsky <1e4b13000fa8777df4cefd2fd8215187e3deb062@aldebaran-robotics.com>

aldebaran/libqi-java,aldebaran/libqi-java,aldebaran/libqi-java