Fix comment about ref directive

Author: 38elements

packages/lit-dev-content/site/docs/templates/directives.md

@@ -1683,7 +1683,7 @@ will be called bound to the host element automatically.
 class MyElement extends LitElement {
 
   render() {
-    // Passing ref directive a change callback
+    // Passing a change callback to ref directive
     return html`<input ${ref(this.inputChanged)}>`;
   }
 
@@ -1697,7 +1697,7 @@ class MyElement extends LitElement {
 class MyElement extends LitElement {
 
   render() {
-    // Passing ref directive a change callback
+    // Passing a change callback to ref directive
     return html`<input ${ref(this.inputChanged)}>`;
   }