Change metacrate description for crates.io

[sffc]

This description shows up on our crates.io page and in search results:

https://crates.io/crates/icu

It doesn't say anything about ICU4X. I was working with @FrankYFTang today who thought we hadn't uploaded anything to crates.io because it wasn't evident in search results that the crate named icu is ICU4X.

This is especially important since the second search result is @filmil's rust_icu, which is ICU4C (and it says so in its description).

[sffc]

I think it will be a better use of time to just set aside 10 minutes of meeting time to wordsmith this together, rather than throwing drafts back and forth.

[sffc]

https://github.com/unicode-org/icu4x/pull/5215

Agreed description of the icu crate: "ICU4X: International Components for Unicode, written in Rust"

Description of the icu4x crate: "For ICU4X, see the icu crate."

For comparison, rust_icu: "Native bindings to the ICU4C library from Unicode."

• @echeran That description makes it sound like this is ICU4C but in Rust.
• @robertbastian That's what ICU4X is, kind-of.
• @echeran The APIs are different, for example.
• @Manishearth ICU4X is intended as this newer thing.
• @echeran And if you want ICU4C, you can use @filmil's rust_icu.
• @echeran Overall I am okay with saying we are a variant of ICU; we've taken a lot of inspiration from it.

Decision:

• Merge this PR
• Also update the description of the icu4x crate as written above, but this cannot be in a PR because the crate does not exist in the repo.

LGTM: @sffc @Manishearth @echeran @robertbastian

[sffc]

I made a new issue to follow-up on changing the icu4x crate description: https://github.com/unicode-org/icu4x/issues/5579