Bump xmlhttprequest-ssl and browser-sync in /docs

Bumps [xmlhttprequest-ssl](https://github.com/mjwwit/node-XMLHttpRequest) to 2.0.0 and updates ancestor dependency [browser-sync](https://github.com/BrowserSync/browser-sync). These dependencies need to be updated together.


Updates `xmlhttprequest-ssl` from 1.5.5 to 2.0.0
- [Commits](mjwwit/node-XMLHttpRequest@1.5.5...2.0.0)

Updates `browser-sync` from 2.26.7 to 2.29.3
- [Release notes](https://github.com/BrowserSync/browser-sync/releases)
- [Changelog](https://github.com/BrowserSync/browser-sync/blob/master/CHANGELOG.md)
- [Commits](BrowserSync/browser-sync@v2.26.7...v2.29.3)

---
updated-dependencies:
- dependency-name: xmlhttprequest-ssl
  dependency-type: indirect
- dependency-name: browser-sync
  dependency-type: direct:development
...

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