[Need support]: Fix stale plugins directory reference in discover-plugins guide

[TKaltofen]

What and why

docs/guides/02-discover-plugins.md tells readers to "Browse the plugins/ directory for community and official plugins", but the repository has no plugins/ directory. Community and enterprise packages live under mloda/community/ and mloda/enterprise/. A newcomer following the guide hits a dead end on the very first step.

Pointers

• docs/guides/02-discover-plugins.md, section "Finding Available Plugins"
• Actual package locations: mloda/community/, mloda/enterprise/, plus config/packages.toml for the full package list

Steps

1. Update the section to point at the real locations (mloda/community/, mloda/enterprise/) and mention config/packages.toml as the package catalog.
2. Skim the rest of the guide for other stale paths.
3. Run python scripts/lint_docs.py.

Acceptance criteria

• The guide no longer references the non-existent plugins/ directory.
• python scripts/lint_docs.py exits 0.

Notes

This project uses semantic versioning driven by Conventional Commits, so the PR title matters: use docs: fix stale plugins directory reference.

New to the project? This issue is a good entry point, we are happy to help in the comments.

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