docs: refactor README

[tyler36]

The Issue

A recently issue on Discord raised some areas for improvement in the currently documentation.

Overview by @rfay:

I do think we should add:

• No gateway/502 might mean you haven't done ddev browsersync
• How to add a config.browsersync_extras.yaml that adds web_extra_daemons to auto start

The documentation is little fragmented and immature. As one fo the first addons created, it has not benefited from recent styles and trends in the addon community.

How This PR Solves The Issue

This PR is a comprehensive refactor of the README.MD.
It

• standardizes Browsersync brand name
• simplifies "Getting Started"
• consolidates snippets into a "Intergration" section
• expands and consolidates a "Troubleshooting" section
• adds a snippet for auto-starting Browsersync

Manual Testing Instructions

Automated Testing Overview

Related Issue Link(s)

Fixes #3

Release/Deployment Notes

[rfay]

Looks great to me. Thanks for all your work on this!