ICU-22922 initial ICU 77 download page; incomplete

[markusicu]

First cut of the download page. To be refined.
Not yet linked from other pages.
Also add known issues to the ICU 76 download page.

Checklist

• Required: Issue filed: ICU-22922
• Required: The PR title must be prefixed with a JIRA Issue number. Example: "ICU-1234 Fix xyz"
• Required: Each commit message must be prefixed with a JIRA Issue number. Example: "ICU-1234 Fix xyz"
• Issue accepted (done by Technical Committee after discussion)
• Tests included, if applicable
• API docs and/or User Guide docs changed or added, if applicable

[richgillam]

Looks good!

[richgillam]

Not sure what this is supposed to be telling me.

[markusicu]

I am trying to say that this has been a relatively recent thing which we are now reverting

[richgillam]

I guess it's the "fully conform to Unicode 16" thing that's throwing me. We diverged from Unicode 16 and now we're going back into sync with it? Or something else?

[markusicu]

The root rules want to match the Unicode segmentation specs.
Sometimes CLDR & ICU experiment with changes before we upstream them back into Unicode proper.
This is a change that hadn't even been discussed with the UTC, and feedback has been negative, and the UTC disagreed with upstreaming this change, so it was decided to revert it in CLDR & ICU.
We should have done this as part of the Unicode 16 update, but missed it.
See the 2024-03-11 design-wg meeting minutes.

(In that meeting, we also agreed to introduce segmentation profiles, but we haven't designed those yet.)

[echeran]

Looks good so far. RSLGTM

[markusicu]

I made a few updates. I think this is as much as I can do now. Please re-stamp?

[richgillam]

I like the new wording.

[jira-pull-request-webhook]

Hooray! The files in the branch are the same across the force-push. 😃

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