Joystick Button Functions Corrections

- The [Joystick Button Functions](https://www.ardusub.com/reference/ardusub/joystick-setup-page.html#joystick-button-functions) section is missing descriptions for:
- `servo_#_max_momentary` and `servo_#_min_momentary`
- ` servo_#_min_toggle` and `servo_#_max_toggle`
- `relay_#_momentary `
- `relay_4_on/off/toggle`
- also `input_hold_toggle` should be `input_hold_set`

Open the Joystick Button Functions section at the linked ArduSub documentation page and compare its entries with the requested names. Add descriptions for the listed servo and relay functions, and change input_hold_toggle to input_hold_set; done means every requested entry is documented and the incorrect name is corrected.

Written by the indexing model from the issue text.