feature request: godoc html output with anchor tags

by **kr@heroku.com**:

<pre>It would be nice to make fine-grain links to sections of
godoc pages. For example, when writing instructions
for the Go buildpack on Heroku, I'd like to link directly
to the “Here's an example directory layout” section of
<a href="http://golang.org/cmd/goinstall/">http://golang.org/cmd/goinstall/</a>.</pre>
