website/docs: maintenance, re-add system settings (#9026)

* update screenshots

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* unrelated: fix api schema

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* required working anchors

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* add system settings page

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* fix broken anchors

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* use client-side-redirects plugin

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* Optimised images with calibre/image-actions

* Revert "use client-side-redirects plugin"

This reverts commit 3103433617.

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

---------

Signed-off-by: Jens Langhammer <jens@goauthentik.io>
Co-authored-by: authentik-automation[bot] <135050075+authentik-automation[bot]@users.noreply.github.com>

website/integrations/sources/google/index.md

@@ -99,4 +99,4 @@ return False
 
 Afterwards, edit the source's enrollment flow (by default _default-source-enrollment_), expand the policies bound to the first stage (_default-source-enrollment-prompt_), and bind the policy created above. Make sure the newly created policy comes before _default-source-enrollment-if-username_. Afterwards, any new logins will automatically have their google email address used as their username.
 
-This can be combined with disallowing users from changing their usernames, see [Configuration](../../../docs/installation/configuration#authentik_default_user_change_username).
+This can be combined with disallowing users from changing their usernames, see [Configuration](../../../docs/core/settings#allow-users-to-change-username).