header.html: fixup cgit link

The strange caching issue still not resolved, so atleast make sure we're
using the working variant.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

docs/header.html

@@ -49,7 +49,7 @@
     <br><a href="/about.html">About</a>
     <br><a href="/news.html">Latest News</a>
     <br><a href="/download.html">Download</a>
-    <br><a href="http://git.buildroot.net/buildroot">Browse Source</a>
+    <br><a href="http://git.buildroot.net/buildroot/">Browse Source</a>
     <br><a href="/git.html">Accessing Source</a>
     <br><a href="https://bugs.uclibc.org/">Bug Tracking</a>
     <br><a href="/docs.html">Documentation</a>