Added extension

[mariusGundersen]

Description

Added link to htmx-json extension

https://github.com/mariusGundersen/htmx-json

Corresponding issue:

Checklist

• I have read the contribution guidelines
• I have targeted this PR against the correct branch (master for website changes, dev for
  source changes)

[NickSdot]

HTMX:

Note that when you are using htmx, on the server side you typically respond with HTML, not JSON. This keeps you firmly within the original web programming model, using Hypertext As The Engine Of Application State without even needing to really understand that concept.

Marius:
hold my beer 🫠