fix varnish comment

according to this link:
https://varnish-cache.org/docs/trunk/reference/vcl.html#comments

a multiline comment should not start on the "/*"-line

Author: OskarStark

http_cache/varnish.rst

@@ -134,8 +134,9 @@ using Varnish 3:
     .. code-block:: varnish3
 
         sub vcl_fetch {
-            /* By default, Varnish3 ignores Cache-Control: no-cache and private
-               https://www.varnish-cache.org/docs/3.0/tutorial/increasing_your_hitrate.html#cache-control
+            /*
+                By default, Varnish3 ignores Cache-Control: no-cache and private
+                https://www.varnish-cache.org/docs/3.0/tutorial/increasing_your_hitrate.html#cache-control
              */
             if (beresp.http.Cache-Control ~ "private" ||
                 beresp.http.Cache-Control ~ "no-cache" ||