Add `composer update` documentation

README.md

@@ -54,4 +54,13 @@ DBP\API\CoreBundle\DbpCoreBundle::class => ['all' => true],
 * Install dependencies: `composer install`
 * Run tests: `composer test`
 * Run linters: `composer run lint`
-* Run cs-fixer: `composer run cs-fix`
+* Run cs-fixer: `composer run cs-fix`
\ No newline at end of file
+
+## Bundle dependencies
+
+Don't forget you need to pull down your dependencies in your main application if you are installing packages in a bundle.
+
+```bash
+# installs dependencies from dbp/api-your-bundle
+composer update dbp/api-your-bundle
+```