Bump the docs group in /docs with 2 updates (#599)

Bumps the docs group in /docs with 2 updates: [markdown-include](https://github.com/cmacmackin/markdown-include) and [mkdocs-material](https://github.com/squidfunk/mkdocs-material).


Updates `markdown-include` from 0.8.0 to 0.8.1
- [Release notes](https://github.com/cmacmackin/markdown-include/releases)
- [Commits](cmacmackin/markdown-include@v0.8.0...v0.8.1)

Updates `mkdocs-material` from 8.5.11 to 9.4.6
- [Release notes](https://github.com/squidfunk/mkdocs-material/releases)
- [Changelog](https://github.com/squidfunk/mkdocs-material/blob/master/CHANGELOG)
- [Upgrade guide](https://github.com/squidfunk/mkdocs-material/blob/master/docs/upgrade.md)
- [Commits](squidfunk/mkdocs-material@8.5.11...9.4.6)

---
updated-dependencies:
- dependency-name: markdown-include
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: docs
- dependency-name: mkdocs-material
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: docs
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

docs/requirements.txt

@@ -1,4 +1,4 @@
-markdown-include==0.8.0
+markdown-include==0.8.1
 mike==1.1.2
 mkdocs-exclude==1.0.2
-mkdocs-material==8.5.11
+mkdocs-material==9.4.6