Add note abour pre-loaded configs

Author: danbarr

docs/toolhive/guides-ui/network-isolation.mdx

@@ -15,6 +15,13 @@ When you install an MCP server in ToolHive, you can optionally enable _network
 isolation_. This feature restricts the MCP server's network access to only the
 resources you specify.
 
+:::note
+
+Network isolation currently supports HTTP and HTTPS connections only. Other
+protocols are not supported.
+
+:::
+
 ## Enabling network isolation
 
 Currently, network isolation is available for MCP servers installed from the
@@ -23,7 +30,10 @@ ToolHive registry.
 During the MCP server installation, select the **Network isolation** tab in the
 configuration form. Click the toggle to enable it.
 
-When network isolation is enabled, you can specify the following:
+When you enable network isolation, any safe default configuration defined in the
+registry is pre-loaded in the form. You can accept these defaults or customize
+the settings to specify which hosts and ports the MCP server is allowed to
+access:
 
 - **Allowed hosts**:\
   A list of hostnames or IP addresses that the MCP server is allowed to access.