Deprecate NewDocument and NewDocumentFromResponse

[mna]

The documentation should mention that NewDocument(url) and NewDocumentFromResponse(httpResponse) are just helpers for quick prototyping/testing, but for "production" code, the HTTP handling should be done outside goquery, and call NewDocumentFromReader(io.Reader) when needed.

Many recent issues are raised because people expect a wide array of behaviour from those 2 functions which shouldn't have been added in the first place. Maybe they should be properly deprecated (as explained here: https://rakyll.org/deprecated/).

At the very least the docs should mention that "advanced" usage of those functions is not recommended. WIth better wording of course.

[ghost]

I am sorry I don'n use goQuery. I just newb TT