Update OpenAPI spec links to use GitHub URLs

[julia-script]

Problem
Open Api specs urls on the llms.txt file are not pointing to the actual resources, these specs tend to be very useful both for humans and llms.

Note: after running the scripts/generate-llms.ts script, other lines were added too, I'm not sure if they were intentionally excluded or if the script just wasn't ran for a while
Solution

This PR updates the scripts/generate-llms.ts to include full urls to GitHub

Checklist

I've gone through the following:

• I've added an explanation why this change is needed.
• I've added a changeset (pnpm changeset).
• I've added tests for the regression or new feature.
• I've updated the documentation.