Learning WG is now rustc-dev-guide WG

[JohnTitor]

Hi folks! I'm happy to announce that the learning WG has been renamed to the rustc-dev-guide WG.

You may remember this announcement:

Rustc-guide is now rustc-dev-guide

Hi all, As many of you are likely aware the WG-learning has renamed the rustc-guide to rustc-dev-guide. And it is now hosted at https://rustc-dev-guide.rust-lang.org. You can read more at: https://blog.rust-lang.org/inside-rust/2020/03/13/rename-rustc-guide.html Thanks!

And we've also renamed our working group name. The main reasons to rename are to avoid confusion and to reflect that we now focus on improving rustc-dev-guide. See Zulip discussion for more detail.