Hide sidebar on donation page

We want more width for our content and less distraction and ways out.

wiki/src/donate.css

+.sidebar {
+  display: none;
+}

wiki/src/donate.html

 [[!meta title="Donate to Tails"]]
 
 [[!meta stylesheet="bootstrap" rel="stylesheet" title=""]]
+[[!meta stylesheet="donate" rel="stylesheet" title=""]]
 [[!meta script="lib/js/jquery"]] <!-- https://code.jquery.com/jquery-1.9.1.min.js -->
 [[!meta script="lib/js/bootstrap/button"]] <!-- https://github.com/twbs/bootstrap/raw/v3.3.6/js/button.js -->
 [[!meta script="donate"]]