added a small faq to the docs

docs/faq.md

@@ -0,0 +1,40 @@
+There are several questions and issues that come up from time to time. Here are some answers.
+Please note that the existence of some questions is due the application not being perfect in some parts. 
+Many of those shortcomings are planned to be fixed in future release but simply could not be addressed yet due to time limits.
+
+## CSRF Errors
+If you are getting CSRF Errors this is most likely due to a reverse proxy not passing the correct headers.
+
+If you are using swag by linuxserver you might need `proxy_set_header X-Forwarded-Proto $scheme;` in your nginx config.
+If you are using a plain ngix you might need `proxy_set_header Host $http_host;`.
+
+Further discussions can be found in this [Issue #518](https://github.com/vabene1111/recipes/issues/518)
+
+## Images not loading
+If images are not loading this might be related to the same issue as the CSRF Errors. 
+A discussion about that can be found [Issue #452](https://github.com/vabene1111/recipes/issues/452)
+
+The other common issue is that the recommended nginx container is removed from the deployment stack. 
+If removed, the nginx webserver needs to be replaced by something else that servers the /mediafiles/ directory or 
+`GUNICORN_MEDIA` needs to be enabled to allow media serving by the application container itself.
+
+## User Creation
+To create a new user click on your name (top right corner) and select system. There click on invite links and create a new invite link.
+
+It is not possible to create users through the admin because users must be assigned a default group and space.
+
+To change a users space you need to go to the admin and select User Infos. 
+
+If you use an external auth provider or proxy authentication make sure to specify a default group and space in the 
+environment configuration.
+
+## Spaces
+Spaces are a feature used to separate one installation of Tandoor into several parts. 
+In technical terms it is a multi tenant system.
+
+You can compare a space to something like google drive or dropbox. 
+There is only one installation of the Dropbox system, but it handles multiple users without them noticing each other.
+For Tandoor that means all people that work together on one recipe collection can be in one space. 
+If you want to host the collection of your friends family or your neighbor you can create a separate space for them (trough the admin interface).
+
+Sharing between spaces is currently not possible but is planned for future releases.

mkdocs.yml

@@ -40,4 +40,5 @@ nav:
       - Updating: system/updating.md
       - Permission System: system/permissions.md
       - Backup: system/backup.md
-  - Contributing: contribute.md
+  - Contributing: contribute.md
+  - FAQ: faq.md