fix: typo in PwmOut.h (pulsewith -> pulsewidth)

Author: yutotnh

drivers/include/drivers/PwmOut.h

@@ -133,13 +133,13 @@ class PwmOut {
 
     /** Read the PWM pulsewidth
      *  @returns
-     *   The PWM pulsewith, specified in microseconds (int)
+     *   The PWM pulsewidth, specified in microseconds (int)
      */
     int read_pulsewidth_us();
 
     /** Read the PWM pulsewidth
      *  @returns
-     *   The PWM pulsewith, specified in microseconds (int)
+     *   The PWM pulsewidth, specified in microseconds (int)
      */
     MBED_DEPRECATED("use read_pulsewidth_us() instead")
     int read_pulsewitdth_us();