client-go/examples/fake-client: add doc.go to fix go build warnings

The fakeclient package does not have any non-test go files. This
causes `go build` to give a warning: `no non-test Go files in ...`.
This also causes the publishing bot to fail.

This PR adds a dummy doc.go file in the package to avoid this warning.

staging/src/k8s.io/client-go/examples/fake-client/BUILD

@@ -1,8 +1,9 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_test")
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 
 go_test(
     name = "go_default_test",
     srcs = ["main_test.go"],
+    embed = [":go_default_library"],
     deps = [
         "//staging/src/k8s.io/api/core/v1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
@@ -25,3 +26,11 @@ filegroup(
     tags = ["automanaged"],
     visibility = ["//visibility:public"],
 )
+
+go_library(
+    name = "go_default_library",
+    srcs = ["doc.go"],
+    importmap = "k8s.io/kubernetes/vendor/k8s.io/client-go/examples/fake-client",
+    importpath = "k8s.io/client-go/examples/fake-client",
+    visibility = ["//visibility:public"],
+)

staging/src/k8s.io/client-go/examples/fake-client/doc.go

@@ -0,0 +1,20 @@
+/*
+Copyright 2018 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Package fakeclient contains examples on how to use fakeclient in tests.
+// Note: This file is here to avoid warnings on go build since there are no
+// non-test files in this package.
+package fakeclient