[DOCS] llmx-ctx*.txt

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- [ ] Existing documentation (e.g. typos, errors, outdated information)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

**Current Behavior or Documentation Gaps**
The `README` only mentions the existence of `llms-ctx.txt`, but NOT `llms-ctx-full.txt`.

If we use the full version, should we expect better results from Cursor chat/dialogues?

I would like it if the README discussed the tradeoffs of using the "full" data file, e.g. better data for the bot so better dialogues, but more tokens hence more cost.

Also, what is the purpose of `llms.txt`? It doesn't seem to be documented.

**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.

cc @algobait