address review comments, rename file

Author: nikomatsakis

posts/2021-07-14.md renamed to posts/2021-07-14-Rust-2021-public-testing.md

@@ -11,15 +11,15 @@ We are happy to announce that the Rust 2021 edition is entering its **public tes
 
 ### Public testing period
 
-As we enter the public testing period, **we are encouraging adventurous users to try migrating their crates over to Rust 2021.** As always, we expect this to be a largely automated process. The steps to try out the Rust 2021 Edition as follows (more detailed directions can be found [in the Edition Guide](https://doc.rust-lang.org/nightly/edition-guide/editions/transitioning-an-existing-project-to-a-new-edition.html)):
+As we enter the public testing period, **we are encouraging adventurous users to test migrating their crates over to Rust 2021.** As always, we expect this to be a largely automated process. The steps to try out the Rust 2021 Edition as follows (more detailed directions can be found [in the Edition Guide](https://doc.rust-lang.org/nightly/edition-guide/editions/transitioning-an-existing-project-to-a-new-edition.html)):
 
 1. Install the most recent nightly: `rustup update nightly`.
 2. Run `cargo +nightly fix --edition`.
 3. Edit `Cargo.toml` and place `cargo-features = ["edition2021"]` at the top (above `[package]`), and change the edition field to say `edition = "2021"`.
 4. Run `cargo +nightly check` to verify it now works in the new edition.
 
-**Note that Rust 2021 is still unstable, so you can expect bugs and other changes!** We recommend migrating your crates in a temporary copy of your code versus your main branch. If you do encounter problems, or find areas where quality could be improved (missing documentation, confusing error mesages, etc) please [file an issue](https://github.com/rust-lang/rust/issues/new/choose) and tell us about it! Thank you!
+**Note that Rust 2021 is still unstable, so you can expect bugs and other changes!** We recommend migrating your crates in a temporary copy of your code versus your main branch. If you do encounter problems, or find areas where quality could be improved (missing documentation, confusing error messages, etc) please [file an issue](https://github.com/rust-lang/rust/issues/new/choose) and tell us about it! Thank you!
 
 ### What comes next
 
-The public testing period will run until the end of July. We will then take some time to fix bugs and do final preparations. We are targeting stabilization of all Rust 2021 for Rust 1.57, which will be released on December 2nd, 2021. Per the [Rust train release model](https://doc.rust-lang.org/book/appendix-07-nightly-rust.html), that means all features and work must be landed on nightly by September 9th.
+We are targeting stabilization of all Rust 2021 for Rust 1.56, which will be released on October 21st, 2021. Per the [Rust train release model](https://doc.rust-lang.org/book/appendix-07-nightly-rust.html), that means all features and work must be landed on nightly by September 7th.