Only support one block and add to readme

Author: nateconley

README.md

@@ -18,6 +18,12 @@ WordPress.com compatibility is limited to Business tier users only. [How to add
 
 ![Configuring extra fields on your Signup Form (optional)](https://github.com/mailchimp/wordpress/blob/develop/.wordpress-org/screenshot-4.jpg?raw=true)
 
+## Frequently Asked Questions
+
+### Can I have multiple forms on one page?
+
+No, only one form should exist per page, no matter the display type (widget, shortcode, or block).
+
 ## Installation
 
 This section describes how to install the plugin and get started using it.

includes/blocks/mailchimp/block.json

@@ -12,6 +12,7 @@
 	},
 	"supports": {
 		"html": false,
+		"multiple": false,
 		"reusable": true,
 		"align": [ "wide", "full" ],
 		"__experimentalBorder": {

includes/blocks/mailchimp/editor.css

@@ -1,4 +1,4 @@
-/* Leave this blank - wp_add_inline_style relies on this file existing */
+/* Leave this file - wp_add_inline_style relies on this file existing */
 #mc_message {
 	display: none;
 }

readme.txt

@@ -16,6 +16,12 @@ After installation, you’ll log in with your API key, select your Mailchimp lis
 
 WordPress.com compatibility is limited to Business tier users only. [How to add a signup form if you have a WordPress.com site](https://mailchimp.com/help/ways-to-add-a-signup-form-in-wordpress/).
 
+== Frequently Asked Questions ==
+
+= Can I have multiple forms on one page? =
+
+No, only one form should exist per page, no matter the display type (widget, shortcode, or block).
+
 == Installation ==
 
 This section describes how to install the plugin and get started using it.