Update doc.go

Updated to correct version v1beta1

Author: firmsoil

pkg/apis/pipeline/v1beta1/doc.go

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-// Package v1alpha1 contains API Schema definitions for the pipeline v1alpha1 API group
+// Package v1beta1 contains API Schema definitions for the pipeline v1beta1 API group
 // +k8s:openapi-gen=true
 // +k8s:deepcopy-gen=package,register
 // +k8s:conversion-gen=github.com/tektoncd/pipeline/pkg/apis/pipeline