update extension to correctly indicate to linter what is es6 and what…

… is not

index.html

@@ -40,7 +40,7 @@
 				},
 				transpiler: 'plugin-babel'
 			});
-			System.import('js/sample_es6.js');
+			System.import('js/sample.es6.js');
 		</script>
 
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