fixes edit ribbon url

- edit basics.html directly
- in new window

fixes #25

basics.html

@@ -1131,7 +1131,8 @@
 
     <div class="ribbon-wrapper right">
       <div class="ribbon">
-        <a href="https://git.idiv.de/sc/edu/git-seminar">
+        <a href="https://git.idiv.de/sc/edu/git-seminar/edit/master/basics.html"
+            target="_blank">
           edit
         </a>
       </div>