Haxelib.json page doesn't adequately describe the format for the classpath attribute.

http://haxe.org/manual/haxelib-json.html

`classpath` is specified as an attribute, but there is no example and no documentation as to whether it is an array or a single string (or either), and if the latter, how to indicate more than one.

Open the haxelib.json documentation at http://haxe.org/manual/haxelib-json.html and review the classpath attribute section. Clarify whether classpath accepts an array or a string, explain how multiple paths are represented if applicable, and add an example showing the format.

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