add link

doc/sphinx/tutorial/sizing_your_cache.rst

@@ -12,7 +12,7 @@ task. A few things to consider:
    to only cache images a little while or not to cache them at all if
    they are cheap to serve from the backend and you have a limited
    amount of memory.
- * Watch the n_lru_nuked counter with varnishstat or some other
+ * Watch the n_lru_nuked counter with :ref:`varnishstat`_ or some other
    tool. If you have a lot of LRU activity then your cache is evicting
    objects due to space constraints and you should consider increasing
    the size of the cache.