encoding/json: document compact json output in Encoder.Encode
Using the same wording as Compact.
Fixes #67943
Change-Id: I578874f3e917bba1634dd988895e622a5ac78c74
Reviewed-on: https://go-review.googlesource.com/c/go/+/597976
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com>