v1.0.0 to support ISR-based multi-channel PWM for MBED nRF52-based boards (Nano_33_BLE, Nano_33_BLE_Sense, etc), using ArduinoCore-mbed mbed_nano or old mbed (v1.3.2-) core

Initial Releases v1.0.0

1. Initial coding to support Nano-33-BLE or Nano-33-BLE_Sense boards using

• Arduino mbed_nano core 2.5.2+ for NRF52-based board using mbed_nano core such as Nano-33-BLE if you don't use NRF_TIMER_1.
• Arduino mbed core v1.3.2- for NRF52-based board using mbed-RTOS such as Nano-33-BLE if you'd like to use NRF_TIMER_1.

2. The hybrid ISR-based PWM channels can generate from very low (much less than 1Hz) to highest PWM frequencies up to 1000Hz with acceptable accuracy.