Add RISC-V notification group instructions

Author: JohnTitor

src/notification-groups/risc-v.md

@@ -0,0 +1,21 @@
+# RISC-V notification group
+
+**Github Label:** [O-riscv]
+
+[O-riscv]: https://github.com/rust-lang/rust/labels/O-riscv
+
+This list will be used to ask for help both in diagnosing and testing
+RISC-V-related issues as well as suggestions on how to resolve
+interesting questions regarding our RISC-V support.
+
+The group also has an associated Zulip stream (`#t-compiler/risc-v`)
+where people can go to pose questions and discuss RISC-V-specific
+topics.
+
+So, if you are interested in participating, please sign up for the
+RISC-V group! To do so, you open a PR against the [rust-lang/team]
+repository. Just [follow this example][eg], but change the username to
+your own!
+
+[rust-lang/team]: https://github.com/rust-lang/team
+[eg]: https://github.com/rust-lang/team/pull/394