website/integrations: add Paperless-ng instructions (#2225)

* Update instructions

I've updated the steps to provide some clarity around certain areas that tripped me up as a newcomer to authentik trying to follow these instructions.

* Added Paperless

Added authentik instructions for Paperless-ng

* Moved to paperless-ng directory

* Minor update to remove redundant part

Removed example authentik.company as these instructions do not require referencing authentik host name directly.

* Added Paperless-ng

* Typo fix

* Formatting changes

Updated changes based on feedback

website/sidebarsIntegrations.js

@@ -25,6 +25,7 @@ module.exports = {
                 "services/nextcloud/index",
                 "services/onlyoffice/index",
                 "services/opnsense/index",
+                "services/paperless-ng/index",
                 "services/portainer/index",
                 "services/powerdns-admin/index",
                 "services/proxmox-ve/index",