feat(readme): doc minimum required rust version

Author: ashleygwilliams

README.md

@@ -24,6 +24,8 @@ visiting that repo!
 
 ## 🔮 Prerequisities
 
+`wasm-pack` requires version 1.30.0 of Rust of higher.
+
 - [Development Environment](https://rustwasm.github.io/wasm-pack/prerequisites/index.html)
 - [Installation and Getting Started](https://rustwasm.github.io/wasm-pack/getting-started/index.html)