Merge pull request #537 from meven/fix-518-rustup-update

Fix how to update rustup

Author: chriskrycho

templates/tools/install.hbs

@@ -41,7 +41,7 @@
       </p>
       <p>
         If you've installed <code>rustup</code> in the past, you can update
-        your installation by running <code>rustup upgrade</code>.
+        your installation by running <code>rustup update</code>.
       </p>
       <p>
         For more information see the