Add links to examples in drupal docs

As big a fan as I am of the API, there is one little thing I think could be easily improved (I think...what do I know ;p).

I was looking at the hook documentation, and it says, for hook_access, 'For a detailed usage example, see node_example.module', but there is no link. You can't search for it, because it's not a function, so you have to go to files and find it. It's not horribly hard or anything, but how much nicer it would be if you could just click away. :)

Anisa.