docs(changelog): update for v1.29.0 stable release

[rami3l]

This is the 1st PR for the 1.29.0 stable release according to our release process.

This PR will also close #4652 via a dev-guide update.

Checklist

• Bump version in the manifest. (Not required, already done in dist: bump rustup version to v1.29.0 #4513.)
• Update the changelog.
• Draft the release blog post: posts: announce rustup 1.29.0 blog.rust-lang.org#1788

Blocking Issues

• feat(cli/rustup-mode): add "Exit status" section to rustup check --help #4696
• Build failure when targeting powerpc64-unknown-linux-gnu #4707
• rustup check is missing a newline between toolchains and self #4560
• CI failure with the rust-android image #4720

[djc]

We should try to land before release

• platforms: prepare 3.8.0 release rustsec/rustsec#1523

[rami3l]

We should try to land before release

• platforms: prepare 3.8.0 release rustsec/rustsec#1523

@djc Thanks! Waiting for the version bump to happen.

[djc]

We should try to land before release

• platforms: prepare 3.8.0 release rustsec/rustsec#1523

@djc Thanks! Waiting for the version bump to happen.

Huh? It already happened -- see

• Take semver-compatible dependency updates #4704

Or do you mean, from the release team?

[djc]

Wonder if we should wait for #4560 (comment).

[rami3l]

It already happened -- see

• Take semver-compatible dependency updates #4704

@djc Thanks for the link; I got confused probably because I have somehow missed the PR plus there's no incoming link from it... My apologies.

[rami3l]

Wonder if we should wait for #4560 (comment).

@djc I'm okay with this since I have to fix the CI failure at the same time. Could/Should we add this to the list of blocking issues as well?

[rami3l]

@rust-lang/rustup All blocking issues resolved; ready to launch.

[djc]

Go ahead!