Merge pull request #70 from ehuss/archive

Add notice for this repo being archived.

Author: eddyb

README.md

@@ -1,3 +1,9 @@
+# ⚠️ wg-grammar has retired
+
+Future work to establish an official grammar for Rust will likely be handled as part of the [Rust Specification](https://github.com/rust-lang/spec).
+
+----
+
 # wg-grammar
 
 This is the home for the Rust Grammar Working Group. The goal of the working