Fix typos (#534)

whereas is incorrect in this context (and supports->support should agree with the plural "pins") -- I think "12 of which" is more appropriate but another option is "The Due has 54 digital pins, including 12 which support PWM (Pulse Width Modulation)."

Author: omajoshi

content/hardware/02.hero/boards/due/features.md

@@ -13,7 +13,7 @@ Based on the ARM® Cortex®-M3 processor, this 32-bit microcontroller has 84 MHz
 
 <Feature title="54 digital pins" image="hw-pin">
 
-The Due has 54 digital pins, whereas 12 supports PWM (Pulse Width Modulation).
+The Due has 54 digital pins, 12 of which support PWM (Pulse Width Modulation).
 
 </Feature>
 
@@ -36,4 +36,4 @@ The Due comes with two CAN (Controller Area Network) buses.
 
 </Feature>
 
-</FeatureList>
+</FeatureList>