Add STM32Cube HAL PWM Breathing LED example with multi-board support …

[kiranj26]

…for F0 series

[kiranj26]

Hi,

I have other examples apart from LED breathing using PWM such as UART echo, UART Interrupt, UART DMA, UART ring buffer, etc. All these changes are verified on F0 nucleo series controllers manually. if this change looks good to you, I'm happy to contribute these other examples as well.

Thank You, Kiran