rebase from live enviornment

wp/wp-content/mu-plugins/pantheon-mu-plugin/inc/pantheon-multisite-finalize.php

@@ -0,0 +1,57 @@
+<?php
+/**
+ * If a site has multisite enabled, but has not had the final installation
+ * steps completed, alert the user and provide links.
+ *
+ * @package pantheon
+ */
+
+/**
+ * Detects if a user is using the correct upstream and framework and give them appropriate next steps to finalize WPMS setup.
+ *
+ * @return void
+ */
+function pantheon_multisite_install_finalize_message() {
+	?>
+	<div class="notice notice-info is-dismissible">
+		<?php
+		if ( isset( $_ENV['PANTHEON_ENVIRONMENT'] ) ) {
+			if ( getenv( 'FRAMEWORK' ) === 'wordpress_network' ) {
+				?>
+					<p><?php esc_html_e( 'Your WordPress Multisite is almost ready!', 'pantheon' ); ?></p>
+					<p>
+						<?php
+						printf(
+							wp_kses_post(
+								// translators: %s is the link to the Pantheon Multisite Configuration documentation.
+								__( 'Visit <a href="%s">Pantheon Multisite Configuration</a> for documentation on how to finalize configuration of your site network.', 'pantheon' )
+							),
+							'https://pantheon.io/docs/guides/multisite/config/#install-the-wordpress-site-network'
+						);
+						?>
+					</p>
+				<?php
+			} else {
+				?>
+					<p><?php esc_html_e( 'You are trying to configure a WordPress Multisite with a wrong upstream!', 'pantheon' ); ?></p>
+					<p>
+						<?php
+						printf(
+							wp_kses_post(
+								// translators: %s is the link to the Pantheon Support page.
+								__( 'Make sure that you have the correct upstream configuration for WPMS. If you do not have that capability or to check if you are eligible, please <a href="%s">Contact Support</a>.', 'pantheon' )
+							), 'https://pantheon.io/support'
+						);
+						?>
+					</p>
+				<?php
+			}
+		}
+		?>
+	</div>
+
+
+	<?php
+}
+
+add_action( 'admin_notices', 'pantheon_multisite_install_finalize_message' );