New example demonstrating use of TIM1 for 2 channel PWM output

fix platformio uartdemo environment

Added polled ADC example

Added SysTick example

Add Readme instructions for attaching WCH-Link to WSL 

Prevent overwrite of HSITRIM default-value in SystemInit48HSI()

Sync documentation and code for read flash command

 * Document _write

Better Makefile CI, fix Run from RAM assembly, update platformio.ini

Make project PlatformIO-compatible