Update release notes for 1.82.0 to include the tier 2 status for the wasm32-wasip2 target

[alexcrichton]

The Rust 1.81.0 release notes originally had a note that the wasm32-wasip2 target was moved to tier 2. This was because #126967 made it into Rust 1.81 and claims that wasm32-wasip2 is tier 2. Alas there was a bug in that PR which ended up being fixed in #127867 which did not make Rust 1.81. This means that Rust 1.81 did not actually include tier 2 status for wasm32-wasip2 in the sense that you could rustup target add the target.

The blog post release notes have been updated to no longer mention this feature of 1.81 and the release notes on the master branch additionally have been updated as well.

In talking with @pietroalbini he recommended I open an issue to track the release notes for 1.82 and I'm told there are mythical and mysterious labels he'll apply to track everything accordingly. I'll also be here to help answer questions if any arise too!