message: Add min Rust version requirement
diff: @@ -6,6 +6,14 @@ major releases of `cosmwasm`. Note that you can also view the
  ## 0.12 -> 0.13
  +- The minimum Rust supported version for 0.13 is 1.47.0.
  +
  + Verify your Rust version is >= 1.47.0:
  +
  + ```
  + rustc -V
  + ```
  +
  - Update CosmWasm dependencies in Cargo.toml (skip the ones you don't use):
  ```
  