fix issue with parsing markdown notes inside of non-markdown slide #2970

plugin/markdown/plugin.js

@@ -206,7 +206,7 @@ const Plugin = () => {
 
 			var externalPromises = [];
 
-			[].slice.call( scope.querySelectorAll( '[data-markdown]:not([data-markdown-parsed])') ).forEach( function( section, i ) {
+			[].slice.call( scope.querySelectorAll( 'section[data-markdown]:not([data-markdown-parsed])') ).forEach( function( section, i ) {
 
 				if( section.getAttribute( 'data-markdown' ).length ) {