Dead link in ScanCode Toolkit

This link is now dead:
- https://scancode-toolkit.readthedocs.io/en/latest/contribute/contrib_doc.html

It was before at https://web.archive.org/web/20241010170703/https://scancode-toolkit.readthedocs.io/en/latest/contribute/contrib_doc.html

This dead link make the build of VulnerableCode PR fail:
- https://github.com/aboutcode-org/vulnerablecode/actions/runs/20270566875/job/58204969458?pr=2024#step:6:147

>
> Warning, treated as error:
> /home/runner/work/vulnerablecode/vulnerablecode/docs/source/contributing.rst:75:broken link: https://scancode-toolkit.readthedocs.io/en/latest/contribute/contrib_doc.html (404 Client Error: Not Found for url: https://scancode-toolkit.readthedocs.io/en/latest/contribute/contrib_doc.html)
> ( contributing: line 75)

This comes from this doc:

- https://github.com/aboutcode-org/vulnerablecode/blob/32d97245b68768cc456644dd4515f923d193f4df/docs/source/contributing.rst#L76

We should either:
- always create a redirect from old to new doc when renaming or moving files
- OR, check across all the repos for possible dead links and also update the doc there