Remove browser-sync

[nicholasio]

Related Issue/RFC: #327

Description of the Change

As part of the v6 roadmap, we're planning on officially removing browser-sync support.

Alternate Designs

Possible Drawbacks

Verification Process

Checklist:

• [x] I have read the CONTRIBUTING document.
• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my change.
• [ ] All new and existing tests passed.
• [ ] I have added a changeset to my PR. See CONTRIBUTING document for instructions

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 33e628032734c6ae7d8e4fa5df01be98c0e1db3b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
10up-toolkit	Major

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR