Document how to set clipboard-write permission

[acelaya]

As noted in #6155 (comment), this PR documents the need to allow clipboard-write and how to do it, when loading Hypothesis inside an iframe.

This is needed for the various places in which content can be copied to the clipboard.

This is how the rendered content looks like, but it can be tested by running make docs and going to http://127.0.0.1:8000/publishers/embedding/#clipboard-permissions-when-loaded-in-an-iframe

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (a185d1e) 99.44% compared to head (f0f08c2) 99.44%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6156   +/-   ##
=======================================
  Coverage   99.44%   99.44%           
=======================================
  Files         263      263           
  Lines       10099    10099           
  Branches     2412     2412           
=======================================
  Hits        10043    10043           
  Misses         56       56           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[robertknight]

The clipboard-write permission is currently a Chrome-specific requirement, and was removed from the official spec. See w3c/permissions#246 and linked issues. Safari and Firefox only require a user activation. See also https://caniuse.com/?search=clipboard.writeText.

I think we can address this by changing "requires the clipboard-write permission" to "requires the clipboard-write permission in Chrome (but not Safari or Firefox)".

[robertknight]

I commented in w3c/clipboard-apis#163 (comment) to see if anything can be done about changing Chrome's behavior so this extra step isn't needed.

[acelaya]

I think we can address this by changing "requires the clipboard-write permission" to "requires the clipboard-write permission in Chrome (but not Safari or Firefox)".

@robertknight I pushed this.

[robertknight]

I wonder if we should generalize this section to include other permissions that are relevant. The clipboard is the main one, but there is also the fullscreen permission for embedded media.

[acelaya]

Yeah, I thought about that. Let's merge this one and I'll create an issue to extend this and make it more generic.

[acelaya]

Done #6157

[robertknight]

LGTM