Added overview documentation for the radio

Change-Id: I71b072512db51f23b0aed82545b504f9efc824d0
Reviewed-by: Dmytro Poplavskiy <dmytro.poplavskiy@nokia.com>

src/multimedia/radio/qradiodata.cpp

@@ -74,6 +74,8 @@ namespace
     The radio data object will emit signals for any changes in radio data. You can enable or disable
     alternative frequency with setAlternativeFrequenciesEnabled().
 
+    \sa {Radio Overview}
+
 */
 
 

src/multimedia/radio/qradiotuner.cpp

@@ -86,6 +86,7 @@ namespace
     You can change between the frequency bands using setBand() however it is recommended
     that you check to make sure the band is available first using isBandSupported().
 
+    \sa {Radio Overview}
 */