E - New PWA documentation project

[a2sheppy]

Our existing Progressive Web Applications (PWA) documentation is out of date and incomplete. These issues cover creating a replacement set of content based in part on the old but reorganized and substantially improved.

Keep in mind the explainer: https://github.com/w3c/manifest/blob/gh-pages/explainer.md And the specification itself: https://w3c.github.io/manifest

Open question: Does the reference go into the main API reference? The changes to Window should be, but everything else probably not—unless it turns out there's a way to use them from the web.

The documentation plan for this project is in a Google doc.

Acceptance Criteria

• [ ] All articles described by the user stories which are part of this epic
• [ ] All articles have been submitted for reviews as appropriate
• [ ] All BCD updates have been made and PRs have been submitted

[chinikes]

@a2sheppy, @chrisdavidmills , @atopal - Please update the acceptance criteria for this epic. Thanks!