[w3c/manifest] Update (#944)

This change (choose at least one, delete ones that don't apply):

* Breaks existing normative behavior (please add label "breaking")
* Adds new normative requirements
* Adds new normative recommendations or optional items
* Makes editorial changes (changes informative sections, or changes normative sections without changing behavior)
* Is a "chore" (metadata, formatting, fixing warnings, etc).

Implementation commitment (delete if not making normative changes):

* [x] Safari (link to issue)
* [x] Chrome (link to issue)
* [ ] Firefox (link to issue)
* [ ] Edge (public signal)

If change is normative, and it adds or changes a member:

* [ ] [updated JSON schema](https://github.com/SchemaStore/schemastore/blob/master/src/schemas/json/web-manifest.json)

Commit message:

(Fill in. If making normative changes, describe exactly what the behavioral
difference will be.)

Person merging, please make sure that commits are squashed with one of the following as a commit message prefix:



You can view, comment on, or merge this pull request online at:

  https://github.com/w3c/manifest/pull/944

-- Commit Summary --

  * Update

-- File Changes --

    M CONTRIBUTING.md (6)

-- Patch Links --

https://github.com/w3c/manifest/pull/944.patch
https://github.com/w3c/manifest/pull/944.diff

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/w3c/manifest/pull/944