chore(deps): bump js-yaml from 3.13.0 to 3.15.0 in /doc

Bumps [js-yaml](https://github.com/nodeca/js-yaml) from 3.13.0 to 3.15.0.
- [Changelog](https://github.com/nodeca/js-yaml/blob/master/CHANGELOG.md)
- [Commits](nodeca/js-yaml@3.13.0...3.15.0)

---
updated-dependencies:
- dependency-name: js-yaml
  dependency-version: 3.15.0
  dependency-type: indirect
...

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

Author: dependabot[bot]