Add main navigation menu, replace intro blurb with full About page

app/templates/dashboard.hbs

@@ -1,19 +1,3 @@
-{{#if this.showIntroText}}
-  <div id="intro" class={{if this.showDetailsPane "with-details"}}>
-    <h2>
-      Welcome to the contribution dashboard of the
-      <a href="https://kosmos.org" target="_blank" rel="noreferrer noopener">Kosmos</a> project!
-    </h2>
-    <p>
-      If you want to learn more about what the numbers mean and how this works,
-      check out the
-      <a href="https://wiki.kosmos.org/Kredits" target="_blank" rel="noreferrer noopener">Kredits documentation</a>.
-      If you want to start earning kredits for your contributions,
-      <LinkTo @route="signup">create a contributor profile</LinkTo>.
-    </p>
-  </div>
-{{/if}}
-
 <main id="dashboard" class={{if this.showDetailsPane "with-details"}}>
 
   <div id="stats">