[DOCS] More features for the Jupyter+FastHTML demo

[pydanny]

Issue Type

• [ ] Existing documentation (e.g. typos, errors, outdated information)
• [x] Suggest new documentation that is currently missing

Suggested Improvement or New Documentation Content

• [x] Show that we can refresh an HTMX handler by simply executing a different cell, and we don't have to restart the server or re-run HTMX()
• [x] If you modify the home page however, you do have to re-run HTMX() (but not the server).
• [x] Mention we can go to localhost:8000 in another tab to see a full screen view.

Relevant Links

Inspired by https://github.com/AnswerDotAI/fasthtml/pull/481#issuecomment-2384743254

Confirmation
Please confirm the following:

• [x] I have checked the existing issues and pull requests to ensure this documentation issue hasn't been reported before.
• [x] I have read the project's documentation and am confident this issue or suggestion is valid.