Record a short Spec-Up training video demo

In the short-term, we're looking for a recorded video that can be played back and used by new contributors to understand how to get started with [spec-up](https://github.com/decentralized-identity/spec-up). See parent task #59 for other ideas.

For this specific task, the suggestions that came out of TSC were

- @csuwildcat to walk one other person who's entirely new to spec-up on how to get started. (Note: these users might be non-technical, so they might need help with basics like installing NPM, etc.)
- Potentially use a tool like Loom or [Trupeer](https://www.trupeer.ai/) (or any other preferred tool!) when recording which can create additional assets. E.g., Trupeer can create a Markdown document with screenshots, which could then be used in the README or docs in spec-up.
- Another suggestion was to create a shareable [NotebookLM](https://notebooklm.google.com/) guide to using spec-up which people could query/consult.