📝 Update laser/spindle docs link (#23886)

Marlin/Configuration_adv.h

  * You'll need to select a pin for the ON/OFF function and optionally choose a 0-5V
  * hardware PWM pin for the speed control and a pin for the rotation direction.
  *
- * See https://marlinfw.org/docs/configuration/laser_spindle.html for more config details.
+ * See https://marlinfw.org/docs/configuration/2.0.9/laser_spindle.html for more config details.
  */
 //#define SPINDLE_FEATURE
 //#define LASER_FEATURE