Add step by step process for updating API

DEVELOPMENT.md

@@ -186,3 +186,18 @@ pnpm run dev
 Open `localhost:5173` in the browser
 
 If Rust code changes you need to rebuild WASM with `pnpm run build-wasm`.
+
+## Process for introducing API changes
+
+Everything in the same PR.
+
+- Update Rust code.
+- Run `cargo run --bin generate_from_types` in **`./generate`** that will generate **`./schemas/scene.schema.json`**.
+- Run `pnpm run generate-types` in **`./ts`** that will generate **`./ts/live-compositor/src/api.generated.ts`**.
+- Update TypeScript code to support new changes.
+- Update CHANGELOG
+
+> To avoid problems with forgetting about adding some changes to TS, everything that shows up in PR diff for
+  `./ts/live-compositor/src/api.generated.ts` should be addressed in the PR that regenerated those types.
+
+