Update README.md

Closes #17

Author: nickwesselman

shopify_function/README.md

@@ -58,6 +58,16 @@ See the [example] for details on usage, or use the following guide to convert an
 
 1. Add `.output.graphql` to your `.gitignore`.
 
+## Viewing the generated types
+
+To preview the types generated by the `generate_types` macro, use the [`cargo doc`](https://doc.rust-lang.org/cargo/commands/cargo-doc.html) command.
+
+```bash
+cargo doc --open
+```
+
+You can also use the [cargo-expand](https://github.com/dtolnay/cargo-expand) crate to view the generated source, or use the [rust-analyzer](https://marketplace.visualstudio.com/items?itemName=rust-lang.rust-analyzer) VSCode extension to get [IntelliSense](https://code.visualstudio.com/docs/editor/intellisense) for Rust and the generated types.
+
 ---
 License Apache-2.0