[ci skip] Update readme.md

Author: ckormanyos

readme.md

@@ -409,7 +409,7 @@ on core0 toggling `port7` while an endless timer loop on core1
 toggles `port6`. The LED ports togle in near unison at $\frac{1}{2}~\text{Hz}$.
 Self-procured LEDs and resistors need to be fitted in order to observe
 blinky on this particular board. The RISCV coprocessor
-toggles `port17` at a randomly chosen frequency around $\frac{2}{3}~\text{Hz}$
+toggles `port17` at a randomly chosen, visible frequency.
 
 The NXP(R) OM13093 LPC11C24 board ARM(R) Cortex(R)-M0+ configuration
 called `target lpc11c24` toggles the LED on `port0.8`.