Bump immutable from 3.8.2 to 3.8.3 in /docs

Bumps [immutable](https://github.com/immutable-js/immutable-js) from 3.8.2 to 3.8.3.
- [Release notes](https://github.com/immutable-js/immutable-js/releases)
- [Changelog](https://github.com/immutable-js/immutable-js/blob/main/CHANGELOG.md)
- [Commits](immutable-js/immutable-js@v3.8.2...v3.8.3)

---
updated-dependencies:
- dependency-name: immutable
  dependency-version: 3.8.3
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]