Fix documentation of BLE GattCharacteristic
Fix documentation of BLE GattCharacteristic

The constructor doc incorrectly suggested that only short (16-bit)
UUIDs were accepted. The same doc also referred to properties
instead of characteristics. (And to "value length", which seemed to
be completely out of place in the context of the current code.)

infinnovation/mbed-os,HeadsUpDisplayInc/mbed,infinnovation/mbed-os,mbedmicro/mbed,mazimkhan/mbed-os,ryankurte/mbed-os,Archcady/mbed-os,HeadsUpDisplayInc/mbed,karsev/mbed-os,betzw/mbed-os,Archcady/mbed-os,andcor02/mbed-os,c1728p9/mbed-os,CalSol/mbed,mbedmicro/mbed,andcor02/mbed-os,betzw/mbed-os,Archcady/mbed-os,infinnovation/mbed-os,infinnovation/mbed-os,infinnovation/mbed-os,ryankurte/mbed-os,mazimkhan/mbed-os,mazimkhan/mbed-os,ryankurte/mbed-os,mbedmicro/mbed,c1728p9/mbed-os,karsev/mbed-os,Archcady/mbed-os,andcor02/mbed-os,mazimkhan/mbed-os,andcor02/mbed-os,kjbracey-arm/mbed,andcor02/mbed-os,CalSol/mbed,CalSol/mbed,betzw/mbed-os,mazimkhan/mbed-os,HeadsUpDisplayInc/mbed,CalSol/mbed,karsev/mbed-os,CalSol/mbed,betzw/mbed-os,c1728p9/mbed-os,infinnovation/mbed-os,kjbracey-arm/mbed,Archcady/mbed-os,HeadsUpDisplayInc/mbed,mbedmicro/mbed,mazimkhan/mbed-os,karsev/mbed-os,ryankurte/mbed-os,karsev/mbed-os,andcor02/mbed-os,betzw/mbed-os,kjbracey-arm/mbed,c1728p9/mbed-os,Archcady/mbed-os,HeadsUpDisplayInc/mbed,kjbracey-arm/mbed,c1728p9/mbed-os,CalSol/mbed,ryankurte/mbed-os,c1728p9/mbed-os,ryankurte/mbed-os,betzw/mbed-os,karsev/mbed-os,HeadsUpDisplayInc/mbed,mbedmicro/mbed