v1.2.1 to fix DutyCycle bug, etc.

### Releases v1.2.1

1. Fix `DutyCycle` bug. Check [float precisison of DutyCycle only sometimes working #3](khoih-prog/SAMD_Slow_PWM#3)
2. Fix `New Period` display bug. Check [random dropouts #4](khoih-prog/SAMD_Slow_PWM#4)
3. Display informational warning only when `_PWM_LOGLEVEL_` > 3
4. Add support to `Sparkfun Pro nRF52840 Mini`
5. Update examples
6. Update `Packages' Patches`

CONTRIBUTING.md

@@ -15,7 +15,7 @@ If you don't find anything, please [open a new issue](https://github.com/khoih-p
 Please ensure to specify the following:
 
 * Arduino IDE version (e.g. 1.8.19) or Platform.io version
-* `nRF52` Core Version (e.g. Adafruit nRF52 core v1.3.0)
+* `NRF52` Core Version (e.g. Adafruit NRF52 core v1.3.0)
 * Contextual information (e.g. what you were trying to achieve)
 * Simplest possible steps to reproduce
 * Anything that might be relevant in your opinion, such as:
@@ -29,7 +29,7 @@ Please ensure to specify the following:
 Arduino IDE version: 1.8.19
 Arduino NRF52 Core Version 1.3.0
 OS: Ubuntu 20.04 LTS
-Linux xy-Inspiron-3593 5.4.0-99-generic #112-Ubuntu SMP Thu Feb 3 13:50:55 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
+Linux xy-Inspiron-3593 5.4.0-100-generic #113-Ubuntu SMP Thu Feb 3 18:43:29 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
 
 Context:
 I encountered a crash while trying to use the Timer Interrupt.