Fix twenty app dev image (#18852)

as title

packages/twenty-docs/developers/extend/capabilities/apps.mdx

@@ -77,6 +77,18 @@ npx create-twenty-app@latest my-app
 npx create-twenty-app@latest my-app --minimal
 ```
 
+### How to use a local Twenty instance
+
+If you're already running a local Twenty instance, you can connect to it instead of using Docker. Pass the port your local server is listening on (default: `3000`):
+
+```bash filename="Terminal"
+# During scaffolding
+npx create-twenty-app@latest my-app --port 3000
+
+# Or after scaffolding
+yarn twenty remote add --local --port 3000
+```
+
 From here you can:
 
 ```bash filename="Terminal"