menu: rename Logbuch -> Blog to fit all viewports

_includes/header.html

@@ -15,7 +15,7 @@
             <ul class="nav navbar-nav">
                 <li><a href="/">Home</a></li>
                 <li class="divider-vertical"></li>
-                <li><a href="/blog/">Logbuch</a></li>
+                <li><a href="/blog/">Blog</a></li>
                 <li class="divider-vertical"></li>
                 <li><a href="/about.html">&Uuml;ber uns</a></li>
                 <!-- <li class="divider-vertical"></li>