Fix Cache-Control header docs [ci skip]

[iguchi1124]

I saw RFC 2616 and RFC 7234(latest...?), response Cache-Control min-stale directive does not exist. So I updated Cache-Control docs.

[namusyaka]

RFC-2616 has existed in the source yet. Why didn't you update another parts?

[iguchi1124]

I'm care about min-stale directive which is not exist in RFC. At this time I updated only Cache-Control doc.

[namusyaka]

The original issue is that min-stale doesn't exist everywhere, makes sense.
However, the change seems not to be enough. For example, according to RFC-7314, a few headers such as max-stale, min-fresh and etc exsit. Could you double-check the docs?

[iguchi1124]

max-stale, min-fresh and etc exsit

Isn't it a "Request" Cache-Control specification? I think there are not a kind of "Response" Cache-Control.

[namusyaka]

Ah sorry, it's my bad. I understood that your change conform the RFC-7314.
However, Sinatra hasn't refer the RFC-7314, but RFC-2616 instead (You can check the link by grepping 2616 inside sinatra repo). I understand thing that should be updated, but it shouldn't be contained in patch-level release, right?
Also, I'd like to update all things at the same time if possible.

Therefore, if you'd like to merge this change, you should remove only min-stale. Don't update RFC version.

[iguchi1124]

Fixed and squashed on this commit! 308e36b

[namusyaka]

Looks good, thanks!