website: add comparison based on vector.dev's site

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

website/docs/development/local-dev-environment.md

@@ -31,6 +31,20 @@ Most functions and classes have type-hints and docstrings, so it is recommended
 
 By default, no transpiled bundle of the frontend is included. To build the UI, you need Node 12 or newer.
 
+The Frontend also uses a generated API client to talk with the backend. To generate this client, you can use the [openapitools/openapi-generator-cli](https://github.com/OpenAPITools/openapi-generator) CLI tool.
+
+If you want to generate the client without installing anything, run this command:
+
+```shell
+docker run \
+  --rm -v $(pwd):/local \
+  openapitools/openapi-generator-cli generate \
+  -i /local/swagger.yaml \
+  -g typescript-fetch \
+  -o /local/web/api \
+  --additional-properties=typescriptThreePlus=true,supportsES6=true,npmName=authentik-api,npmVersion=1.0.0
+```
+
 To build the UI, run these commands:
 
 ```