For better or worse, I'm convinced that this is the reason that PHP took off the way it did. The documentation was clear, concise, easy to access (perhaps the first example of user friendly URLs I can remember), and effective; That each function had user-submitted (moderated) comments was the icing on the cake.

Being able to look at a function, have clear documentation WITH EXAMPLES was brilliant -- being able to see some of the common questions and resolutions from users was exemplary.

I know that the python docs are largely considered aces, but I have yet to see a language reference as good as the PHP documents. I hate the language, but it was the first language I could actually learn from its own documentation.