cmd/go: add release notes for go telemetry, and telemetry env values

This change fills in the release notes for the go telemetry command as
well as the unsettable GOTELEMETRY and GOTELEMETRYDIR go env values.

For #67111

Change-Id: Id6943f79f7ab2457787e1639d8d5fb1c1e2649dc
Reviewed-on: https://go-review.googlesource.com/c/go/+/587923
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

doc/next/3-tools.md

@@ -24,8 +24,12 @@ The `go` `list` `-m` `-json` command now includes new `Sum` and `GoModSum` field
 This is similar to the existing behavior of the `go` `mod` `download` `-json` command.
 
 <!-- go.dev/issue/67111 ("cmd/go: add go telemetry subcommand") -->
-The new `go` `telemetry` command should be documented here,
-as well as `GOTELEMETRY` and `GOTELEMETRYDIR` environment variables.
+The new `go` `telemetry` command can be used to view and configure the telemetry collection
+mode. Without arguments, it displays the current mode. With `local`, `on`, or `off`, it sets
+the collection mode. `go` `env` now lists two values: the `GOTELEMETRY` value, which
+contains the telemetry collection mode, and the `GOTELEMETRYDIR` value setting which contains
+the directory telemetry data and configuration are written to.
+
 <!-- go.dev/issue/58894 ("all: add opt-in transparent telemetry to Go toolchain") -->
 <!-- TODO: document Go 1.23 behavior (from https://go.dev/cl/559199, https://go.dev/cl/559519, https://go.dev/cl/559795, https://go.dev/cl/562715, https://go.dev/cl/562735, https://go.dev/cl/564555, https://go.dev/cl/570679, https://go.dev/cl/570736, https://go.dev/cl/582695, https://go.dev/cl/584276, https://go.dev/cl/585235, https://go.dev/cl/586138) -->