Customize: Improve the wording for Site Icon control intro.

Props michelleweber, dlh, menakas, melchoyce.
Fixes #40430.
Built from https://develop.svn.wordpress.org/trunk@41749


git-svn-id: http://core.svn.wordpress.org/trunk@41583 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-customize-manager.php

@@ -4340,9 +4340,10 @@ final class WP_Customize_Manager {
 		$this->add_control( new WP_Customize_Site_Icon_Control( $this, 'site_icon', array(
 			'label'       => __( 'Site Icon' ),
 			'description' => sprintf(
+				'<p>' . __( 'Site Icons are what you see in browser tabs, bookmark bars, and within the WordPress mobile apps. Upload one here!' ) . '</p>' .
 				/* translators: %s: site icon size in pixels */
-				__( 'The Site Icon is used as a browser and app icon for your site. Icons must be square, and at least %s pixels wide and tall.' ),
-				'<strong>512</strong>'
+				'<p>' . __( 'Site Icons should be square and at least %s pixels.' ) . '</p>',
+				'<strong>512 &times; 512</strong>'
 			),
 			'section'     => 'title_tagline',
 			'priority'    => 60,

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-alpha-41748';
+$wp_version = '4.9-alpha-41749';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.