Update RealIps Description (bitwarden#1980)

Describe the syntax of the real_ips configuration key with an example, to prevent type errors in the `setup` container when parsing `config.yml`

Author: notnamed

util/Setup/Configuration.cs

@@ -97,7 +97,9 @@ public class Configuration
 
         [Description("Defines \"real\" IPs in nginx.conf. Useful for defining proxy servers that forward the \n" +
             "client IP address.\n" +
-            "Learn more: https://nginx.org/en/docs/http/ngx_http_realip_module.html")]
+            "Learn more: https://nginx.org/en/docs/http/ngx_http_realip_module.html\n\n" +
+            "Defined as a dictionary, e.g.:\n" +
+            "real_ips: ['10.10.0.0/24', '172.16.0.0/16']")]
         public List<string> RealIps { get; set; }
 
         [Description("Enable Key Connector (https://bitwarden.com/help/article/deploy-key-connector)")]