Add link to Joe Heck’s Combine notes

Author: RoyalIcing

apps/components_guide_web/lib/components_guide_web/templates/links/index.html.eex

@@ -56,6 +56,7 @@
 
       <h3 class="mt-6 mb-2 text-2xl leading-normal italic">Tools and libraries for Combine</h3>
       <ul class="list-disc">
+        <li><%= link "Joe Heck’s in-depth Combine notes.", to: "https://heckj.github.io/swiftui-notes/" %></li>
         <li><%= link "Entwine: Testing tools and utilities for Apple's Combine framework.", to: "https://github.com/tcldr/Entwine" %></li>
       </ul>
     </article>