Bump the docs-dependencies group across 1 directory with 3 updates

Bumps the docs-dependencies group with 2 updates in the /docs/starlight directory: [@astrojs/starlight](https://github.com/withastro/starlight/tree/HEAD/packages/starlight) and [sharp](https://github.com/lovell/sharp).


Updates `@astrojs/starlight` from 0.39.2 to 0.40.0
- [Release notes](https://github.com/withastro/starlight/releases)
- [Changelog](https://github.com/withastro/starlight/blob/main/packages/starlight/CHANGELOG.md)
- [Commits](https://github.com/withastro/starlight/commits/@astrojs/starlight@0.40.0/packages/starlight)

Updates `astro` from 6.3.7 to 6.4.7
- [Release notes](https://github.com/withastro/astro/releases)
- [Changelog](https://github.com/withastro/astro/blob/main/packages/astro/CHANGELOG.md)
- [Commits](https://github.com/withastro/astro/commits/astro@6.4.7/packages/astro)

Updates `sharp` from 0.34.5 to 0.35.1
- [Release notes](https://github.com/lovell/sharp/releases)
- [Commits](lovell/sharp@v0.34.5...v0.35.1)

---
updated-dependencies:
- dependency-name: "@astrojs/starlight"
  dependency-version: 0.40.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: docs-dependencies
- dependency-name: astro
  dependency-version: 6.4.7
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: docs-dependencies
- dependency-name: sharp
  dependency-version: 0.35.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: docs-dependencies
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]