Add @public tag

[steel]

Even though public is implicit by default, this gives extra flexibility to explicitly mark classes and methods as public.

[inossidabile]

Why would you add a tag that does nothing? What stops you from just using it without this PR?

[steel]

I'm generating JSON output and using the @public tag to explicitly signify that a class is public so it can be exposed in another level of documentation. It's in JS Doc for this exact situation. http://usejsdoc.org/tags-public.html

[steel]

I'm open to suggestions as well.

[mdiebolt]

I think this is useful for styling documentation that is part of the public interface differently than the internals.

A consumer might only need documentation for public pieces, while a maintainer could use insight into internals.

[steel]

Thanks @inossidabile