Rollup merge of #141139 - jieyouxu:fix-rfl, r=Urgau

Fix Rust for Linux ping group label

Noticed in rust-lang/rust#140966 (comment). Seems like a broken label can cause the triagebot ping message to not be issued.

See rust-lang/triagebot#1992.

```@rustbot``` label: +A-rust-for-linux

Author: fmease

src/notification-groups/rust-for-linux.md

@@ -1,9 +1,9 @@
 # Rust for Linux notification group
 
-**Github Label:** [O-rfl] <br>
+**Github Label:** [A-rust-for-linux] <br>
 **Ping command:** `@rustbot ping rfl`
 
-[O-rfl]: https://github.com/rust-lang/rust/labels/O-rfl
+[A-rust-for-linux]: https://github.com/rust-lang/rust/labels/A-rust-for-linux
 
 This list will be used to notify [Rust for Linux (RfL)][rfl] maintainers
 when the compiler or the standard library changes in a way that would