link directly to the install guide in the footer

Author: pietroalbini

app/templates/application.hbs

@@ -122,7 +122,7 @@
 </main>
 
 <footer class='after-main-links'>
-  {{#link-to 'install'}}Install{{/link-to}}
+  <a href='https://doc.rust-lang.org/cargo/getting-started/installation.html'>Install</a>
   <span class="sep">|</span>
   <a href='https://doc.rust-lang.org/cargo/'>Getting Started</a>
   <span class="sep">|</span>