minor links and maning fixes

[r2dedios]

Summary

Fix stale repository names and broken URLs left behind after two upstream renames that were not propagated across the codebase.

Issues found and fixes applied

1. Stale catalog repo name (agentic-collections-catalog -> agentic-catalog)

The repository was renamed to agentic-catalog, but the old name agentic-collections-catalog was still referenced across 12 files. This caused broken links for GitHub badges, license URLs,
raw content URLs, the website footer, and installation commands.

• Files fixed: README.md, AGENTS.md, docs/README.md, docs/index.html, docs/app.js, scripts/build_website.py, scripts/check_site.py, scripts/generate_collection_pages.py, Makefile,
  pyproject.toml, uv.lock

2. Stale skills source repo name (agentic-collections-skills -> agentic-plugins)

The skills source repository was renamed to agentic-plugins, but all seven module entries in the marketplace file and documentation references still pointed to agentic-collections-skills.
This would cause lola install to fail since git clone would target a non-existent repository.

• Files fixed: marketplace/rh-agentic-collection.yml (all 7 module repository fields), README.md, AGENTS.md

3. Incorrect marketplace top-level url field

The marketplace url pointed to the skills repo (agentic-collections-skills) instead of the catalog repo itself (agentic-catalog). The marketplace name and description also still used the
old "collections" terminology, and the generated marketplace alias in generate_collection_pages.py was rh-agentic-collections instead of rh-agentic-catalog.

• Files fixed: marketplace/rh-agentic-collection.yml (top-level name, description, url), scripts/generate_collection_pages.py

4. Missing trailing newline in marketplace file

rh-agentic-collection.yml was missing a newline at end of file (POSIX compliance).

[dmartinol]

Thank you! /lgtm