Update the PWM register configuration docs

Docs/10. PWM/10.2 pwm-configuration.txt

@@ -13,4 +13,6 @@
     --> `Machine Cycle` = 4 / 20MHz = 200ns
     --> `PWM Period` = 1 / `PWM Frequency`
 
-    => Set the 10bit duty cycle value in CCP1CON and CCPR1L.
+    => Set the 10bit duty cycle value in CCP1CON and CCPR1L.
+    --> The CCPR1L contains the 8 most significant bits.
+    --> The CCP1CON contains the 2 least significant bits.