Added table describing observed frequency per processor speed

docs/group_assignments/group2/assignment4.md

@@ -96,4 +96,10 @@ Figure: XIAO SAMD2 measurements
 The signal frequencies for 
 XIAO RP2040, XIAO ESP32C3, and XIAO SAMD2 are 
      10.2 MHz,    3.81 MHz, and     3.69 MHz respectively.
+    
+Since the processor clock speeds are different, it is interesting to calculate the signal frequency per processor speed.
+This is shown in the following table.
+Table: Signal frequencies, the processor clock speeds, and the ratio of the signal frequency to the processor speed.
+![signalperclockspeed](./assets/assignment4/schematic_photos/speeds_table.jpg)
+