"sectors" in custom target on STM32WLE5CC

Hi,

You can find some comment about the sectors information in CMSIS device support pack here:

And CMSIS official document here:
https://www.keil.com/pack/doc/CMSIS/Pack/html/createPack_DFP.html#cp_FlashProgrammingAlgorithm

You can also find similar topic here:

The STM32WLE5CC is not listed in the https://github.com/ARMmbed/mbed-os/blob/master/tools/arm_pack_manager/index.json, but you can probably use (or copy and modify) STM32WL55JCIx config.