Update the "addon" docs page to use node-gyp and gyp files

[TooTallNate]

Since we're trying to phase out node-waf this is a good thing to do.

It should also talk about the "build_files" variable from #3099.

[zzak]

+1 I'd like to help, the plan is to remove node-waf completely right?

[TooTallNate]

the plan is to remove node-waf completely right?

@zzak Eventually. node-gyp and node-waf can live alongside one another without any harm so there's no rush. Once the large majority of modules in the wild are using node-gyp then we'll start considering it.

Any changes you make to the addon docs in this direction would be appreciated, though. Let me know!

[zzak]

@TooTallNate, I'll rewrite the "Hello World" and "Addon Patterns" intro to include node-gyp docs, with favor to gyp. That way both will co-exist for the time being. Incase anyone really wants to use node-waf or is maintaining a legacy addon, until node-waf is completely phased out.