Cortex-M Quickstart needs attention.

[LucianoMoretti]

Sorry if this is the wrong place:
The Cortex-M Quickstart guide Docs.rs build 0.3.4 is failing with the following:
error[E0658]: The attribute 'panic_implementation' is currently unknown to the compiler and may have meaning added to it in the future (see issue #29642) --> .cargo/registry/src/github.com-1ecc6299db9ec823/panic-semihosting-0.3.0/src/lib.rs:71:1 | 71 | #[panic_implementation] | ^^^^^^^^^^^^^^^^^^^^^^^ | = help: add #![feature(custom_attribute)] to the crate attributes to enable

Also, the last built version (0.3.1) references using Nightly, which is no longer required for the Cortex-M.

[jonas-schievink]

Quickstart is hosted at https://github.com/rust-embedded/cortex-m-quickstart. It is no longer published to crates.io (as it isn't a crate). The repo is up to date.

[jamesmunns]

I'm going to close this issue. Let me know if anyone thinks we should re-open!