Update m5stack_dial.md only one board_url....

Author: RetiredWizard

_board/m5stack_dial.md

@@ -6,7 +6,6 @@ name: "Dial - Smart Rotary Knob with Touch Screen"
 manufacturer: "M5Stack"
 board_url:
  - "https://www.adafruit.com/product/5966"
- - "https://docs.m5stack.com/en/core/M5Dial"
 board_image: "m5stack_dial.jpg"
 date_added: 2024-02-19
 family: esp32s3