Add example implementations for compatible MCUs list (#15935)

* Add example implementations for compatible MCUs list

* Update docs/compatible_microcontrollers.md

Co-authored-by: Nick Brassel <nick@tzarc.org>

Co-authored-by: Nick Brassel <nick@tzarc.org>

docs/compatible_microcontrollers.md

@@ -1,14 +1,18 @@
 # Compatible Microcontrollers
 
-QMK runs on any USB-capable AVR or ARM microcontroller with enough flash space - generally 32kB or more, though it will *just* squeeze into 16kB with most features disabled.
+QMK runs on any USB-capable AVR or ARM microcontroller with enough flash space - generally 32kB+ for AVR, and 64kB+ for ARM. With significant disabling of features, QMK may *just* squeeze into 16kB AVR MCUs.
 
 ## Atmel AVR
 
 The following use [LUFA](https://www.fourwalledcubicle.com/LUFA.php) as the USB stack:
 
 * [ATmega16U2](https://www.microchip.com/wwwproducts/en/ATmega16U2) / [ATmega32U2](https://www.microchip.com/wwwproducts/en/ATmega32U2)
 * [ATmega16U4](https://www.microchip.com/wwwproducts/en/ATmega16U4) / [ATmega32U4](https://www.microchip.com/wwwproducts/en/ATmega32U4)
+  * SparkFun Pro Micro (and clones)
+  * PJRC Teensy 2.0
+  * Adafruit Feather 32U4
 * [AT90USB64](https://www.microchip.com/wwwproducts/en/AT90USB646) / [AT90USB128](https://www.microchip.com/wwwproducts/en/AT90USB1286)
+  * PJRC Teensy++ 2.0
 * [AT90USB162](https://www.microchip.com/wwwproducts/en/AT90USB162)
 
 Certain MCUs which do not have native USB will use [V-USB](https://www.obdev.at/products/vusb/index.html) instead:
@@ -25,11 +29,15 @@ You can also use any ARM chip with USB that [ChibiOS](https://www.chibios.org) s
 
  * [STM32F0x2](https://www.st.com/en/microcontrollers-microprocessors/stm32f0x2.html)
  * [STM32F103](https://www.st.com/en/microcontrollers-microprocessors/stm32f103.html)
+   * Bluepill (with STM32duino bootloader)
  * [STM32F303](https://www.st.com/en/microcontrollers-microprocessors/stm32f303.html)
+   * QMK Proton-C
  * [STM32F401](https://www.st.com/en/microcontrollers-microprocessors/stm32f401.html)
+   * WeAct Blackpill
  * [STM32F405](https://www.st.com/en/microcontrollers-microprocessors/stm32f405-415.html)
  * [STM32F407](https://www.st.com/en/microcontrollers-microprocessors/stm32f407-417.html)
  * [STM32F411](https://www.st.com/en/microcontrollers-microprocessors/stm32f411.html)
+   * WeAct Blackpill
  * [STM32F446](https://www.st.com/en/microcontrollers-microprocessors/stm32f446.html)
  * [STM32G431](https://www.st.com/en/microcontrollers-microprocessors/stm32g4x1.html)
  * [STM32G474](https://www.st.com/en/microcontrollers-microprocessors/stm32g4x4.html)
@@ -45,13 +53,16 @@ You can also use any ARM chip with USB that [ChibiOS](https://www.chibios.org) s
 ### NXP (Kinetis)
 
  * [MKL26Z64](https://www.nxp.com/products/processors-and-microcontrollers/arm-microcontrollers/general-purpose-mcus/kl-series-cortex-m0-plus/kinetis-kl2x-72-96-mhz-usb-ultra-low-power-microcontrollers-mcus-based-on-arm-cortex-m0-plus-core:KL2x)
+   * PJRC Teensy LC
  * [MK20DX128](https://www.nxp.com/products/processors-and-microcontrollers/arm-microcontrollers/general-purpose-mcus/k-series-cortex-m4/k2x-usb/kinetis-k20-50-mhz-full-speed-usb-mixed-signal-integration-microcontrollers-based-on-arm-cortex-m4-core:K20_50)
  * [MK20DX256](https://www.nxp.com/products/processors-and-microcontrollers/arm-microcontrollers/general-purpose-mcus/k-series-cortex-m4/k2x-usb/kinetis-k20-72-mhz-full-speed-usb-mixed-signal-integration-microcontrollers-mcus-based-on-arm-cortex-m4-core:K20_72)
+   * PJRC Teensy 3.2
  * [MK66FX1M0](https://www.nxp.com/products/processors-and-microcontrollers/arm-microcontrollers/general-purpose-mcus/k-series-cortex-m4/k6x-ethernet/kinetis-k66-180-mhz-dual-high-speed-full-speed-usbs-2mb-flash-microcontrollers-mcus-based-on-arm-cortex-m4-core:K66_180)
+   * PJRC Teensy 3.6
 
 ## Atmel ATSAM
 
-There is limited support for one of Atmel's ATSAM microcontrollers, that being the [ATSAMD51J18A](https://www.microchip.com/wwwproducts/en/ATSAMD51J18A) used by the [Massdrop keyboards](https://github.com/qmk/qmk_firmware/tree/master/keyboards/massdrop).
+There is limited support for one of Atmel's ATSAM microcontrollers, that being the [ATSAMD51J18A](https://www.microchip.com/wwwproducts/en/ATSAMD51J18A) used by the [Massdrop keyboards](https://github.com/qmk/qmk_firmware/tree/master/keyboards/massdrop). However, it is not recommended to design a board with this microcontroller as the support is quite specialized to Massdrop hardware.
 
 ## RISC-V