Use Go canonical import paths

Add canonical imports only in existing doc.go files.
https://golang.org/doc/go1.4#canonicalimports

Fixes #29014

pkg/genericapiserver/doc.go

@@ -20,4 +20,4 @@ limitations under the License.
 // pkg/master and pkg/apiserver) here.
 // We plan to move this package into a separate repo on github once it is done.
 // For more details: https://github.com/kubernetes/kubernetes/issues/2742
-package genericapiserver
+package genericapiserver // import "k8s.io/kubernetes/pkg/genericapiserver"

pkg/genericapiserver/options/doc.go

@@ -18,4 +18,4 @@ limitations under the License.
 // server. It takes a minimal set of dependencies and does not reference
 // implementations, in order to ensure it may be reused by multiple components
 // (such as CLI commands that wish to generate or validate config).
-package options
+package options // import "k8s.io/kubernetes/pkg/genericapiserver/options"