fix URLs, include ARM

Author: nikomatsakis

triagebot.toml

@@ -20,7 +20,7 @@ Hey LLVM ICE-breakers! This bug has been identified as a good
 [instructions] for tackling these sorts of bugs. Maybe take a look?
 Thanks! <3
 
-[instructions]: https://rustc-dev-guide.rust-lang.org/ice-breaker/llvm.html
+[instructions]: https://rustc-dev-guide.rust-lang.org/notification-groups/llvm.html
 """
 label = "ICEBreaker-LLVM"
 
@@ -32,7 +32,7 @@ Hey Cleanup Crew ICE-breakers! This bug has been identified as a good
 [instructions] for tackling these sorts of bugs. Maybe take a look?
 Thanks! <3
 
-[instructions]: https://rustc-dev-guide.rust-lang.org/ice-breaker/cleanup-crew.html
+[instructions]: https://rustc-dev-guide.rust-lang.org/notification-groups/cleanup-crew.html
 """
 label = "ICEBreaker-Cleanup-Crew"
 
@@ -46,6 +46,16 @@ Thanks! <3
 """
 label = "O-windows"
 
+[ping.arm]
+message = """\
+Hey ARM Group! This bug has been identified as a good "ARM candidate".
+In case it's useful, here are some [instructions] for tackling these sorts of
+bugs. Maybe take a look?
+Thanks! <3
+[instructions]: https://rust-lang.github.io/rustc-guide/notification-groups/arm.html
+"""
+label = "O-ARM"
+
 [prioritize]
 label = "I-prioritize"
 prioritize_on = ["regression-from-stable-to-stable", "regression-from-stable-to-beta", "regression-from-stable-to-nightly"]