Coldcard MK4 video and docs

[pavlenex]

We'll get MK4 to test and update our docs and video. This issue is to track a progress on that.

Old videos Connecting Coldcard wallet to BTCPay Server / Coldcard wallet and BTCPay Server - PSBT Sending from a wallet airgapped

• [ ] Decide if we want to merge two legacy videos into one and record a new video
• [ ] If we're making only a single video, see what other wallets can be used to record "PSBT in BTCPay video" If we decide for two separate videos:
• [ ] Record a new "How to connect ColdCard to BTCPay" video
• [ ] Record a new "How to use PSBT in BTCPay"

[dennisreimann]

Received mine today! 👍

[webwworthy]

Got mine as well!

[Bas02]

Moving second part of connecting HWW to : https://github.com/btcpayserver/btcpayserver-doc/issues/1232