[Bug]: README files missing from references directory

[rolznz]

Description

When I do npx skills add getAlby/alby-agent-skill there should be a README file inside references/lightning-tools/ but it is for some reason omitted when downloading this way.

https://github.com/vercel-labs/add-skill/blob/main/src/installer.ts#L169

I don't see something in the spec that says we cannot have README files.

Steps to Reproduce

1. Run npx skills add getAlby/alby-agent-skill
2. Look in references/lightning-tools and you will see there is no README.md despite it existing in the repository.

Expected Behavior

README files should not be excluded.

Actual Behavior

README files are excluded.

Version

No response

Node.js Version

No response

Operating System

None

Logs / Error Output