update language of description

inc/pantheon-page-cache.php

@@ -238,7 +238,7 @@ public function default_ttl_field() {
 		$disabled = ( has_filter( 'pantheon_cache_default_max_age' ) ) ? ' disabled' : '';
 		echo wp_kses_post( apply_filters( 'pantheon_cache_default_ttl_field_before_html', '<div class="pantheon_cache_default_max_age">' ) );
 		echo '<h3>' . esc_html__( 'Page Cache Max Age', 'pantheon-cache' ) . '</h3>'; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
-		echo '<p>' . esc_html__( 'Maximum time a cached page will be served. A higher max-age typically improves site performance.', 'pantheon-cache' ) . '</p>'; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
+		echo '<p>' . wp_kses_post( sprintf( __( 'When your site content is updated, <a href="%s">Pantheon Advanced Page Cache</a> clears page cache automatically. This setting determines how long a page will be stored in the Global Content Delivery Network (GCDN) cache before GCDN retrieves the content from WordPress again.', 'pantheon-cache' ), '#' ) ). '</p>'; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
 		echo '<input type="text" name="' . self::SLUG . '[default_ttl]" value="' . $this->options['default_ttl'] . '" size="7" ' . $disabled . ' /> ' . esc_html__( 'seconds', 'pantheon-cache' ); // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
 		echo wp_kses_post( apply_filters( 'pantheon_cache_default_ttl_field_after_html', '</div>' ) );