Small doc improvements suggestions

[Arkadiusz Miśkiewicz]

Hello. Trying auto tap for first time and got few small documentation issues for improvement consideration.

• "See Validate Results for how to validate the offset." - wrong link

• VOC Discord - Auto TAP - also wrong link (at least nothing about auto tap opens in discord)

• "If your version of tap is not validated, please make sure you validate results before using the calculated offset, and let me know if it worked for you!

Then, place this in your printer.cfg

[auto_tap]"

but klipper won't load auto_tap.py extras module without [auto_tap] in printer.cfg, so can't do any validation before adding anything to printer.cfg. Adding empty [auto_tap] section won't work (Option 'tap_version' in section 'auto_tap' must be specified).
so user has to add [auto_tap] tap_version: xyz before validation.

• I guess validation should mention to do homing and quad gantry leveling first