chore(docs): document graphql-codegen script (#1213)

* chore(docs): document graphql-codegen script

* chore(docs): reference codegen.yml

.github/contributing.md

@@ -96,6 +96,20 @@ Eslint config should not be overridden in any packages.
 
 Prettier config should not be overridden in any packages.
 
+#### GraphQL type generation
+
+[GraphQL Code Generator](https://the-guild.dev/graphql/codegen) is used for generating TypeScript types from `schema.graphql` files.
+
+```shell
+./<package>/codegen.yml # GraphQL Code Generator config
+```
+
+The `generate` script should be run if a package's `schema.graphql` file is modified.
+
+```shell
+pnpm --filter <package> generate
+```
+
 #### Testing
 
 [Jest](https://jestjs.io/) is used for testing.

README.md

@@ -82,6 +82,9 @@ pnpm -r build
 # build specific package (e.g. backend):
 pnpm --filter backend build
 
+# generate types from specific package GraphQL schema:
+pnpm --filter backend generate
+
 # run individual tests (e.g. backend)
 pnpm --filter backend test