docs: fix for domain sharding results in failed requests with "Missin…

…g Authorization Header" (apache#24481)

Co-authored-by: Evan Rusackas <evan@preset.io>
Co-authored-by: John Bodley <4567245+john-bodley@users.noreply.github.com>

docs/docs/installation/networking-settings.mdx

@@ -33,6 +33,15 @@ Add the following setting in your `superset_config.py` file:
 
 - `SUPERSET_WEBSERVER_DOMAINS`: list of allowed hostnames for domain sharding feature.
 
+Please create your domain shards as subdomains of your main domain for authorization to
+work properly on new domains. For Example:
+
+- `SUPERSET_WEBSERVER_DOMAINS=['superset-1.mydomain.com','superset-2.mydomain.com','superset-3.mydomain.com','superset-4.mydomain.com']`
+
+or add the following setting in your `superset_config.py` file if domain shards are not subdomains of main domain.
+
+- `SESSION_COOKIE_DOMAIN = '.mydomain.com'`
+
 ### Middleware
 
 Superset allows you to add your own middleware. To add your own middleware, update the