Automatically update dependency version

In the current "Create a Rust project" section, the `Cargo.toml` code references an old version of `cosmwasm-std`:
```toml
cosmwasm-std = { version = "1.0.0-beta8", features = ["staking"] }
```

The reason I am not just creating a PR to fix this is because I am wondering if there might be a better way to automatically keep dependency numbers up-to-date, or if this section should simply use `cargo add cosmwasm-std` instead?