make_sensors.pl: Add \since tag
make_sensors.pl: Add \since tag

Otherwise it is easy to forget about this

Change-Id: Ib1da49c136f3e9cf99f68dd283143fe2fc0eb930
Reviewed-by: Lorn Potter <0e329dfd61bdd4e2b2b708a31f12f199a7656feb@nokia.com>

kobolabs/qtsensors,mer-qt/qtsensors,mer-qt/qtsensors,mer-qt/qtsensors,mer-qt/qtsensors,kobolabs/qtsensors,kobolabs/qtsensors,richardmg/qtsensors,richardmg/qtsensors,richardmg/qtsensors,richardmg/qtsensors,kobolabs/qtsensors,mer-qt/qtsensors,richardmg/qtsensors