Add bootloader section to keyboard template (#13774)

* Add bootloader section to keyboard template

* Apply suggestions from code review

Co-authored-by: Ryan <fauxpark@gmail.com>

Co-authored-by: Ryan <fauxpark@gmail.com>

quantum/template/avr/readme.md

@@ -17,3 +17,11 @@ Flashing example for this keyboard:
     make %KEYBOARD%:default:flash
 
 See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) and the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information. Brand new to QMK? Start with our [Complete Newbs Guide](https://docs.qmk.fm/#/newbs).
+
+## Bootloader
+
+Enter the bootloader in 3 ways:
+
+* **Bootmagic reset**: Hold down the key at (0,0) in the matrix (usually the top left key or Escape) and plug in the keyboard
+* **Physical reset button**: Briefly press the button on the back of the PCB - some may have pads you must short instead
+* **Keycode in layout**: Press the key mapped to `RESET` if it is available

quantum/template/ps2avrgb/readme.md

@@ -16,6 +16,13 @@ Flashing example for this keyboard ([after setting up the bootloadHID flashing e
 
     make %KEYBOARD%:default:flash
 
-**Reset Key**: Hold down the key located at *LOCATION*, commonly programmed as *KEY* while plugging in the keyboard.
-
 See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) and the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information. Brand new to QMK? Start with our [Complete Newbs Guide](https://docs.qmk.fm/#/newbs).
+
+## Bootloader
+
+Enter the bootloader in 3 ways:
+
+* **Bootmagic reset**: Hold down the key at (0,0) in the matrix (usually the top left key or Escape) and plug in the keyboard
+* **BootloadHID reset**: Hold down the key connected to the `A0` and `B0` pins on the MCU if it is known (often top left or bottom left) and plug in the keyboard
+* **Physical reset button**: Briefly press the button on the back of the PCB - some may have pads you must short instead
+* **Keycode in layout**: Press the key mapped to `RESET` if it is available