v1.2.0 to optimize speed and add `PWM_SpeedTest`

### Releases v1.2.0

1. Optimize speed with new `setPWM_DCPercentageInt_manual` function to improve speed almost 50% compared to `setPWM_DCPercentage_manual` of previous `v1.1.0`
2. Add example [PWM_SpeedTest](https://github.com/khoih-prog/ATtiny_PWM/tree/main/examples/PWM_SpeedTest) to demo the better speed of new `setPWM_DCPercentageInt_manual` function
3. Improve `README.md` so that links can be used in other sites, such as PIO

v1.1.0 for new `PWM_manual` example, etc.

1. Add example [PWM_manual](https://github.com/khoih-prog/ATtiny_PWM/tree/main/examples/PWM_manual) to demo how to correctly use PWM to generate waveform. Check [About DCValue in setPWM_manual #2](khoih-prog/AVR_PWM#2)
2. Add function `setPWM_DCPercentage_manual()` to facilitate the setting PWM DC manually by using `DCPercentage`, instead of `absolute DCValue` depending on varying PWMPeriod
3. Catch low frequency error and use lowest permissible frequency

v1.0.1 to add `PWM_StepperControl` example

### Releases v1.0.1

1. Add example [PWM_StepperControl](https://github.com/khoih-prog/ATtiny_PWM/tree/main/examples/PWM_StepperControl) to demo how to control Stepper Motor using PWM

v1.0.0 for hardware-PWM on ATtiny boards

### Initial Releases v1.0.0

1. Initial coding to support Arduino **AVR ATtiny-based boards (ATtiny3217, etc.)** using [**megaTinyCore**](https://github.com/SpenceKonde/megaTinyCore)