Create a triagebot ping group for Rust for Linux

Author: Kobzol

triagebot.toml

@@ -122,6 +122,17 @@ issues).
 """
 label = "O-apple"
 
+[ping.rust-for-linux]
+alias = ["rfl"]
+message = """\
+Hey Rust for Linux group! It looks like something broke the Rust for Linux integration.
+Could you try to take a look?
+In case it's useful, here are some [instructions] for tackling these sorts of issues.
+
+[instructions]: https://rustc-dev-guide.rust-lang.org/notification-groups/rust-for-linux.html
+"""
+label = "O-rfl"
+
 [prioritize]
 label = "I-prioritize"