Links with "target=_blank" should prevent phishing attacks

Author: mvegter

docs/_includes/footer.html

@@ -8,7 +8,7 @@
     </div>
     <div class="footer-title">
      Sponsored by
-      <a href="https://container-solutions.com/" target="_blank">
+      <a href="https://container-solutions.com/" target="_blank" rel="noopener noreferrer">
         <img src="{{ site.baseurl }}/assets/images/cs.png">
       </a>
     </div>

docs/_includes/header.html

@@ -1,9 +1,9 @@
 <div class="header-strip {{ page.collection }} {{ page.name | split: "." | first }}">
   <div class="header navbar navbar-expand-lg">
     <div class="logo">
-       <a href="https://github.com/ContainerSolutions/java-operator-sdk/blob/master/README.md" target="_blank">
+       <a href="https://github.com/ContainerSolutions/java-operator-sdk/blob/master/README.md" target="_blank" rel="noopener noreferrer">
       <img src="{{ site.baseurl }}/assets/images/GitHub-Mark-64px.png">
-       <a href="https://discord.gg/DacEhAy" target="_blank">
+       <a href="https://discord.gg/DacEhAy" target="_blank" rel="noopener noreferrer">
       <img src="{{ site.baseurl }}/assets/images/discord.png">
       </a>
     </div>