Add a rustc version badge
diff --git a/README.md b/README.md
index 6cf18be..ab45488 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,7 @@
[](https://travis-ci.org/dtolnay/syn)
[](https://crates.io/crates/syn)
[](https://docs.rs/syn/0.12/syn/)
+[](https://blog.rust-lang.org/2017/02/02/Rust-1.15.html)
Syn is a parsing library for parsing a stream of Rust tokens into a syntax tree
of Rust source code.