encoding/json: clarify how to encode a cue.Value to JSON

Fixes #3231.

Signed-off-by: Daniel Martí <[email protected]>
Change-Id: I35402c3f892a38fa57031a48c4900fffbc688fd8
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1215556
TryBot-Result: CUEcueckoo <[email protected]>
Unity-Result: CUE porcuepine <[email protected]>
Reviewed-by: Roger Peppe <[email protected]>

Author: mvdan

encoding/json/json.go

@@ -12,7 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package json converts JSON to and from CUE.
+// Package json converts JSON to CUE.
+// To convert CUE to JSON, use [encoding/json.Marshal] on a [cue.Value].
 package json
 
 import (