net/http: update Response.Trailer doc

I updated this in the previous commit (https://golang.org/cl/17931)
but noticed a typo. and it still wasn't great.

The Go 1.5 text was too brief to know how to use it:

    // Trailer maps trailer keys to values, in the same
    // format as the header.

Change-Id: I33c49b6a4a7a3596735a4cc7865ad625809da900
Reviewed-on: https://go-review.googlesource.com/17932
Reviewed-by: Russ Cox <rsc@golang.org>

diff --git a/src/net/http/response.go b/src/net/http/response.go
index 0e39ed3a3a299c1930d83345825efe0040e93b74..57ae364f57bbeded8c424b651b9edf15489b1904 100644 (file)
--- a/src/net/http/response.go
+++ b/src/net/http/response.go
@@ -72,14 +72,18 @@ type Response struct {
        // ReadResponse nor Response.Write ever closes a connection.
        Close bool
 
-       // Trailer maps trailer keys to values, in the same
-       // format as the header.
+       // Trailer maps trailer keys to values in the same
+       // format as Header.
        //
-       // The Trailer initially contains only the server's
-       // pre-declared trailer keys, but with nil values. Trailer
-       // must not be access concurrently with Read calls on the
-       // Body. After Body.Read has returned io.EOF, Trailer can be read
-       // again and will contain any values sent by the server.
+       // The Trailer initially contains only nil values, one for
+       // each key specified in the server's "Trailer" header
+       // value. Those values are not added to Header.
+       //
+       // Trailer must not be accessed concurrently with Read calls
+       // on the Body.
+       //
+       // After Body.Read has returned io.EOF, Trailer will contain
+       // any trailer values sent by the server.
        Trailer Header
 
        // The Request that was sent to obtain this Response.