translate: add notice to recommend v3 gapic client for new projects
// See the License for the specific language governing permissions and
// limitations under the License.
-// Package translate is a client for the Google Translation API.
+// Package translate is the v2 client for the Google Translation API.
+//
+// PLEASE NOTE: We recommend using the new v3 client for new projects:
+// https://cloud.google.com/go/translate/apiv3.
+//
// See https://cloud.google.com/translation for details.
package translate
