net/http: display connect methods table properly in `go doc`

net/http: display connect methods table properly in `go doc`

When run `go doc -u http.connectMethod`, the whole table is treated as
a single long line. This commit inserts `\t` at the begining of each line,
so the table can be displayed properly in `go doc`.

Change-Id: I6408efd31f84c113e81167d62e1791643000d629
Reviewed-on: https://go-review.googlesource.com/74651
Reviewed-by: Ian Lance Taylor <iant@golang.org>