cmd/doc: why not show doc for individual struct fields?

[willfaught]

Go v1.8 enabled go doc to show the doc for an individual interface method, so why not do the same for struct fields? Like:

$ go doc net/http RoundTripper.RoundTrip
// RoundTrip executes a single HTTP transaction, returning
// a Response for the provided Request.
//
// RoundTrip should not attempt to interpret the response. In
// particular, RoundTrip must return err == nil if it obtained
// a response, regardless of the response's HTTP status code.
// A non-nil err should be reserved for failure to obtain a
// response. Similarly, RoundTrip should not attempt to
// handle higher-level protocol details such as redirects,
// authentication, or cookies.
//
// RoundTrip should not modify the request, except for
// consuming and closing the Request's Body.
//
// RoundTrip must always close the body, including on errors,
// but depending on the implementation may do so in a separate
// goroutine even after RoundTrip returns. This means that
// callers wanting to reuse the body for subsequent requests
// must arrange to wait for the Close call before doing so.
//
// The Request's URL and Header fields must be initialized.
func RoundTrip(*Request) (*Response, error)

$ go doc net/http Response.Header
// Header maps header keys to values. If the response had multiple
// headers with the same key, they may be concatenated, with comma
// delimiters.  (Section 4.2 of RFC 2616 requires that multiple headers
// be semantically equivalent to a comma-delimited sequence.) Values
// duplicated by other fields in this struct (e.g., ContentLength) are
// omitted from Header.
//
// Keys in the map are canonicalized (see CanonicalHeaderKey).
var Header Header

[luigi-riefolo]

I'd be happy to work on this if the enhancement gets approved.

[bradfitz]

To @robpike for decision.

[robpike]

Makes sense, shouldn't be too hard.

[gopherbot]

CL https://golang.org/cl/38438 mentions this issue.