added link in readme

firmwares/marlin/README.md

@@ -26,3 +26,5 @@ I've modified the `*_PROBE_BED_POSITION` defines to use probe offsets
 ```
 
 > NOTES : PID values are for my 0.4mm steel nozzle and borosillicate bed. Ender 3 is mainly stock, the only hardware updates atm are dampers on all stepper and TLSmoothers on X,Y & Z.
+
+Some explainations about how it used id in the [Wiki](https://git.dahwa.fr/3DPrinting/Tips/wiki/TouchMi)