Suggested new Api* Attributes

[wwwlicious]

Might be worth suggesting a couple of new Api attributes to add to servicestack, if not, they can just be added to introspec.

Name	AllowMultiple	ApplyTo	Suggested Signature
Category	Yes	Assembly, Class, Method	[ApiCategory(string category)]
Example	Yes	Method	[ApiExample(string url, string body)]
Tag	Yes	Assembly, Class, Method	[ApiTag(params string[] tags)]