docs: update README to remove old examples and reference mud-area tutorial

[berkeleynerd]

Update README to remove references to legacy example binaries and point to the mud-area tutorial and CLI usage instead.

Acceptance

• Docs consistent with current repo (no broken references to old examples).

[berkeleynerd]

Closed: tutorial content migrated to a different repository; tracking moved.

[berkeleynerd]

Reopening: this is not part of the docs(tutorial) series. Keeping this README update in this repo.