Tracking issue for the Macos notification group

[hkratz]

The MCP for creating a Macos notification group (#470) was accepted. This issue tracks the progress on the steps for actually creating it (see Rust Forge documentation).

Progress:

• File a tracking issue in the [rust-lang/compiler-team] repository to collect your progress.
• Create a PR against the [rust-lang/team] repository adding the notification group. ➡️ Add macos notification group team#670
• Configure the [rust-lang/rust] repository to accept triagebot commands for this group.
• Create a PR for the rustc-dev-guide amending the notification group section to mention your group.
• Create a sample PR for the [rust-lang/team] repository showing how one can add oneself. This will be referenced by your blog post to show people how to join.
• Create a Zulip stream for the notification group. If you don't have the permission to do, you can ask on [#t-compiler/wg-meta].
• Write an announcement blog post for Inside Rust and open a PR against blog.rust-lang.org.