docs: update FAQ and default example

Author: Joxit

README.md

@@ -68,11 +68,11 @@ Checkout all options in [Available options](#available-options) section.
 -   Why the default nginx `Host` is set to `$http_host` ?
     -   This fixes the issue [#88](https://github.com/Joxit/docker-registry-ui/issues/88). More about this in [#113](https://github.com/Joxit/docker-registry-ui/issues/113).
 -   Why OPTIONS (aka preflight requests) and DELETE fails with 401 status code (using Basic Auth) ?
-    -   This is caused by a bug in docker registry, it returns 401 status requests on preflight requests, this breaks [W3C preflight-request specification](https://www.w3.org/TR/cors/#preflight-request). I suggest to have your UI on the same domain than your registry e.g. registry.example.com/ui/ **or** use `NGINX_PROXY_PASS_URL` **or** configure a nginx/apache/haproxy in front of your registry that returns 200 on each OPTIONS requests. (see [#104](https://github.com/Joxit/docker-registry-ui/issues/104), [#204](https://github.com/Joxit/docker-registry-ui/issues/204), [#207](https://github.com/Joxit/docker-registry-ui/issues/207), [#214](https://github.com/Joxit/docker-registry-ui/issues/214), [#266](https://github.com/Joxit/docker-registry-ui/issues/266)).
+    -   This is caused by a bug in docker registry, it returns 401 status requests on preflight requests, this breaks [W3C preflight-request specification](https://www.w3.org/TR/cors/#preflight-request). I contacted docker registry maintainers and this will never be fixed ([distribution/distribution#4458](https://github.com/distribution/distribution/issues/4458)). I suggest to have your UI on the same domain than your registry e.g. registry.example.com/ui/ **or** use `NGINX_PROXY_PASS_URL` **or** configure a nginx/apache/haproxy in front of your registry that returns 200 on each OPTIONS requests. (see [#104](https://github.com/Joxit/docker-registry-ui/issues/104), [#204](https://github.com/Joxit/docker-registry-ui/issues/204), [#207](https://github.com/Joxit/docker-registry-ui/issues/207), [#214](https://github.com/Joxit/docker-registry-ui/issues/214), [#266](https://github.com/Joxit/docker-registry-ui/issues/266), [#278](https://github.com/Joxit/docker-registry-ui/issues/278)).
 -   Can I use the docker registry ui as a standalone application (with Electron) ?
     -   Yes, check out the example [here](https://github.com/Joxit/docker-registry-ui/tree/main/examples/electron). (see [#129](https://github.com/Joxit/docker-registry-ui/pull/129))
 -   I deleted images through the UI, but they are still present on the server. How can I delete them?
-    - When you delete an image with the UI, only the reference is deleted and not the content. To remove dangling images, you need to run the garbage collector of the registry with the command `registry garbage-collect config.yml` or `docker exec registry registry garbage-collect config.yml`. (see [#77](https://github.com/Joxit/docker-registry-ui/issues/77) [#147](https://github.com/Joxit/docker-registry-ui/issues/147))
+    - When you delete an image with the UI, only the reference is deleted and not the content. To remove dangling images, you need to run the garbage collector of the registry with the command `registry garbage-collect config.yml` or `docker exec registry registry garbage-collect config.yml`. (see [#77](https://github.com/Joxit/docker-registry-ui/issues/77), [#147](https://github.com/Joxit/docker-registry-ui/issues/147))
 -   Why when I delete one tag, all tags with the same SHA are deleted ?
     - This a docker registry API limitation, there is only one way to [delete images with tag](https://docs.docker.com/registry/spec/api/#deleting-an-image), it's by its `name` and its `manifest` (it's a sha of the content). So when you delete a tag, this will delete all tags of this image with the same SHA/manifest.
 -   Can I run the container with an unprivileged user ?
@@ -171,7 +171,7 @@ services:
     image: registry:2.8.2
     restart: always
     environment:
-      REGISTRY_HTTP_HEADERS_Access-Control-Allow-Origin: '[http://registry.example.com]'
+      REGISTRY_HTTP_HEADERS_Access-Control-Allow-Origin: '[http://registry-ui.example.com]'
       REGISTRY_HTTP_HEADERS_Access-Control-Allow-Methods: '[HEAD,GET,OPTIONS,DELETE]'
       REGISTRY_HTTP_HEADERS_Access-Control-Allow-Credentials: '[true]'
       REGISTRY_HTTP_HEADERS_Access-Control-Allow-Headers: '[Authorization,Accept,Cache-Control]'
@@ -195,7 +195,7 @@ If your docker registry need credentials, you will need to send these HEADERS (y
 ```yml
 http:
   headers:
-    Access-Control-Allow-Origin: ['http://registry.example.com']
+    Access-Control-Allow-Origin: ['http://registry-ui.example.com']
     Access-Control-Allow-Credentials: [true]
     Access-Control-Allow-Headers: ['Authorization', 'Accept', 'Cache-Control']
     Access-Control-Allow-Methods: ['HEAD', 'GET', 'OPTIONS'] # Optional