Add split 3x5_3 keyword; clarify boot button

keyboards/tutte_coxeter_36k/readme.md

@@ -3,10 +3,10 @@
 ![Partial Tutte-Coxeter Graph (26/30 vertices, 36/45 edges)](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvS5QfAl7YotptMtpu0nG8XOHOsqG2vocUFF2sRgrn_QwAcUQNhDkctHt_42rQor3Bb5tbAW6FiOsYqv2craP086HMTuAqWk9U0A4yOeEsQkhyphenhyphenUxoayJWf5e-N3_Jg1TC1p9YAiVPTK02pEVCUu3hl72REIk5BAjXgZGoF7T-NWQ28iRirwFs6yzFzAe0/w200-h194/Screenshot%202025-05-28%20at%2014.59.35.png)
 
 This is firmware for an Raspberry Pi Pico PR2040 controller monoblock 36 key design
-(three rows of five, and three thumb keys, for each hand). This is a *diode-free*
-design with a sparse 13 by 13 scanning matrix designed using a partial
+(split 3x5_3 - three rows of five, and three thumb keys, for each hand). This is a
+*diode-free* design with a sparse 13 by 13 scanning matrix designed using a partial
 [Tutte-Coxeter](https://en.wikipedia.org/wiki/Tutte%E2%80%93Coxeter_graph) graph
-(using only 26 vertices or GPIO pins with 36 edges or keys - see this
+(using only 26 vertices or GPIO pins, with 36 edges or keys - see this
 [blog post](https://astrobeano.blogspot.com/2025/05/ergo-mech-keyboard-wiring-using-tutte-coxeter-graph.html)
 for background, although the final pin selection and trace routing changed).
 
@@ -34,5 +34,5 @@ See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_to
 Enter the bootloader in 3 ways:
 
 * **Bootmagic reset**: Hold down the key at (0,0) in the matrix (bottom left key, Qwerty `z`) 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
+* **Physical reset button**: Briefly press the button on the back of the controller (if physically accessible)
 * **Keycode in layout**: Press the key mapped to `QK_BOOT` if it is available