CLDR-17185 Just update dates for readme and spec

[pedberg-icu]

CLDR-17185

• This PR completes the ticket.

Just updated the dates for the README.md and spec. Checked to see whether the spec mods needed any updates for the recent specs changes, but they already seemed to be covered by the existing mods section.

(I want to do this for beta3 integration, but it is also sort of a test PR to make sure I can do CLDR work on my newly set up personal system)

ALLOW_MANY_COMMITS=true

[CLAassistant]

All committers have signed the CLA.

[srl295]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.You have signed the CLA already but the status is still pending? Let us recheck it.

Suspicious. Who's this @pedberg-icu :)

[pedberg-icu]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.You have signed the CLA already but the status is still pending? Let us recheck it.

Suspicious. Who's this @pedberg-icu :)

Part of the point of this PR was to make sure that I was actually forced to re-sign the CLA as an individual contributor... and I was! And I have now done so.

[srl295]

and LGTM also