Fix "Create new" for sitegroups in Settings

Needs to reference updated slugs for taxonomy and post_type

includes/class-wp-push-syndication-server.php

@@ -489,7 +489,7 @@ class WP_Push_Syndication_Server {
 		// if there are no sitegroups defined return
 		if( empty( $sitegroups ) ) {
 			echo '<p>' . esc_html__( 'No sitegroups defined yet. You must group your sites into sitegroups to syndicate content', 'push-syndication' ) . '</p>';
-			echo '<p><a href="' . esc_url( get_admin_url() . 'edit-tags.php?taxonomy=sitegroups&post_type=site' ) . '" target="_blank" >' . esc_html__( 'Create new', 'push-syndication' ) . '</a></p>';
+			echo '<p><a href="' . esc_url( get_admin_url() . 'edit-tags.php?taxonomy=syn_sitegroup&post_type=syn_site' ) . '" target="_blank" >' . esc_html__( 'Create new', 'push-syndication' ) . '</a></p>';
 			return;
 		}