Update README

keyboards/keebio/cepstrum/readme.md

@@ -15,6 +15,13 @@ Example of flashing this keyboard:
 
 Handedness detection is already hardwired onto the PCB, so no need to deal with `EE_HANDS` or flashing .eep files.
 
-See [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) then the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information.
+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 one of these ways:
+
+* **Physical reset button**: Press and hold the button on the back of the PCB for at least 2 seconds and let go, or double-press the button
+* **Keycode in layout**: Press the key mapped to `QK_BOOT` if it is available
 
 A build guide for this keyboard can be found here: [Keebio Build Guides](https://docs.keeb.io)