Add note about recommended pins to avoid with additional libraries

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reference issue #7 some libraries and functions conflict with PWM use, avoiding PWM pins on Timer 1 on the uno or Timer 5,or 2,on the mega

• UNO: when you use the Servo Library you can’t use PWM on Pin 9, 10
• MEGA: it is a little bit more difficult
  • For the first 12 servos timer 5 will be used (losing PWM on Pins 44,45,46)
  • For 13-24 servos timer 5 and 1 will be used (losing PWM on Pins 11,12,44,45,46)
  • For 25-36 servos timer 5, 1 and 3 will be used (losing PWM on Pins 2,3,5,11,12,44,45,46)
  • For 37-48 servos all 16bit timers 5,1,3 and 4 will be used (losing all PWM pins).

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Close as reopened in #15