go doc <packageName>/<packageName+funcName/typeName>
返回一个包的文档或者某一个函数或者类型的文档。这里后面指定的路径不一定要完整或者正确。
例如，查看 time 包的文档。
$ go doc time
package time // import "time"
Package time provides functionality for measuring and displaying time.
The calendrical calculations always assume a Gregorian calendar, with no
leap seconds.
Monotonic Clocks
Operating systems provide both a “wall clock,” which is subject to changes
for clock synchronization, and a “monotonic clock,” which is not. The
general rule is that the wall clock is for telling time and the monotonic或者是一个方法：
$ go doc time.Since
func Since(t Time) Duration
Since returns the time elapsed since t. It is shorthand for
time.Now().Sub(t).有或者输入一个不完整的名称：
$ go doc json.decode
func (dec *Decoder) Decode(v interface{}) error
Decode reads the next JSON-encoded value from its input and stores it in the
value pointed to by v.
See the documentation for Unmarshal for details about the conversion of JSON
into a Go value.godoc 提供了一个相互链接的 HTML 页面服务。在 "https://golang.org/pkg" 的 godoc 服务器覆盖了标准库。
在 "https://godoc.org" 的 godoc 服务器提供了数千个可供搜索的开源包索引。
如果你想浏览自己的包，也可以在你的工作区间运行一个 godoc 实例。在执行下面的命令后，在浏览器中访问 http://localhost:8000/pkg:
godoc -http :8000加上 -analysis=type 和 -analysis=pointer 标记是文档的内容更加丰富。同时提供源代码的高级静态分析结果。