UX: Add title to iframe elements

Fixes template linting errors

assets/javascripts/discourse/templates/components/amazon-product-links.hbs

@@ -1,12 +1,28 @@
 {{#if showAd}}
   {{#if site.mobileView}}
     <div class="amazon-product-links-label" style={{adTitleStyleMobile}}><h2>{{i18n "adplugin.advertisement_label"}}</h2></div>
-    <iframe style={{adWrapperStyleMobile}} marginwidth="0" marginheight="0" scrolling="no" frameborder="0" src={{userInputMobile}}>
+    <iframe
+      style={{adWrapperStyleMobile}}
+      marginwidth="0"
+      marginheight="0"
+      scrolling="no"
+      frameborder="0"
+      src={{userInputMobile}}
+      title={{i18n "adplugin.advertisement_label"}}
+    >
     </iframe>
   {{else}}
     <div class="amazon-product-links-label"><h2>{{i18n "adplugin.advertisement_label"}}</h2></div>
     <div class="container" align="center">
-      <iframe style={{adWrapperStyle}} marginwidth="0" marginheight="0" scrolling="no" frameborder="0" src={{userInput}}>
+      <iframe
+        style={{adWrapperStyle}}
+        marginwidth="0"
+        marginheight="0"
+        scrolling="no"
+        frameborder="0"
+        src={{userInput}}
+        title={{i18n "adplugin.advertisement_label"}}
+      >
       </iframe>
     </div>
   {{/if}}