build(deps): bump soupsieve from 2.8 to 2.8.4 in /docs

Bumps [soupsieve](https://github.com/facelessuser/soupsieve) from 2.8 to 2.8.4.
- [Release notes](https://github.com/facelessuser/soupsieve/releases)
- [Commits](facelessuser/soupsieve@2.8...2.8.4)

---
updated-dependencies:
- dependency-name: soupsieve
  dependency-version: 2.8.4
  dependency-type: indirect
...

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

Author: dependabot[bot]