add missing rel to link

Author: locks

app/templates/logos.hbs

@@ -3,7 +3,7 @@
   <section aria-labelledby="branding" class="branding-section">
     <h1 id="branding">Branding</h1>
     <p>The Ember brand and associated assets are part of a meticulously curated experience. We take great pride in what our team and community have helped bring to life, and ask that you follow our guidelines to ensure consistency across all Ember properties.</p>
-    <p><a href="/pdfs/Ember-Brand-Guidelines.pdf" target="_blank">Download brand guidelines (PDF)</a></p>
+    <p><a href="/pdfs/Ember-Brand-Guidelines.pdf" target="_blank" rel="noopener noreferrer">Download brand guidelines (PDF)</a></p>
   </section>
 
   <section aria-labelledby="logos" class="branding-section">