HeaderMap docs show using a string value

[seanmonstar]

The documentation of HeaderMap shows using strings for values, which works in the doc tests because HeaderMap<T> is generic over the value. However, if people try to use the same examples in real code, it won't work, because Request and Response both use HeaderMap<HeaderValue>. The docs should probably be updated to show using HeaderValues.

I also kind of wonder if the generic T will cause problems elsewhere. If someone just needs to view some headers, and writes &HeaderMap, and sees the complaint about a missing generic, will they easily be able to determine it should be &HeaderMap<HeaderValue?

Should we export a type alias instead?

[carllerche]

It looks like this will be fixed as part of #86?

[seanmonstar]

No, the docs still show using a HeaderMap<&'static str>.

[carllerche]

Docs can be fixed post 0.1, so I will remove the milestone.

[seanmonstar]

This is pretty much done. Glancing through, it looks like HeaderMap::get_mut shows using a String instead of HeaderValue, but since you can't mutate a HeaderValue, it'd be a less useful example...