Add example for kustomize build {url}

examples/remoteBuild.md

@@ -0,0 +1,58 @@
+# remote targets
+
+`kustomize build` can be run against a url. The effect is the same as cloing the repo, checking out the specified ref,
+then running `kustomize build` against the desired directory in the local copy.
+
+Take `github.com/kubernetes-sigs/kustomize//examples/multibases?ref=v1.0.6` as an example.
+According to [multibases](multibases/README.md) demo, this kustomization contains three Pod objects with names as
+`cluster-a-dev-myapp-pod`, `cluster-a-stag-myapp-pod`, `cluster-a-prod-myapp-pod`.
+Running `kustomize build` against the url gives the same output.
+
+<!-- @remoteBuild @test -->
+```
+target=github.com/kubernetes-sigs/kustomize//examples/multibases?ref=v1.0.6
+test 3 == \
+  $(kustomize build $target | grep cluster-a-.*-myapp-pod | wc -l); \
+  echo $?
+```
+
+A base can also be specified as a URL:
+
+<!-- @createOverlay @test -->
+```
+DEMO_HOME=$(mktemp -d)
+
+cat <<EOF >$DEMO_HOME/kustomization.yaml
+bases:
+- github.com/kubernetes-sigs/kustomize//examples/multibases?ref=v1.0.6
+namePrefix: remote-
+EOF
+```
+Running `kustomize build $DEMO_HOME` and confirm the output contains three Pods and all have `remote-` prefix.
+<!-- @remoteBases @test -->
+```
+test 3 == \
+  $(kustomize build $DEMO_HOME | grep remote-.*-myapp-pod | wc -l); \
+  echo $?
+```
+
+## URL format
+The url should follow
+[hashicorp/go-getter URL format](https://github.com/hashicorp/go-getter#url-format).
+Here are some example urls pointing to Github repos following this convention.
+
+- a repo with a root level kustomization.yaml
+
+  `github.com/Liujingfang1/mysql`
+- a repo with a root level kustomization.yaml on branch test
+
+  `github.com/Liujingfang1/mysql?ref=test`
+- a subdirectory in a repo on version v1.0.6
+
+  `github.com/kubernetes-sigs/kustomize//examples/multibases?ref=v1.0.6`
+- a subdirectory in a repo on branch repoUrl2
+
+  `github.com/Liujingfang1/kustomize//examples/helloWorld?ref=repoUrl2`
+- a subdirectory in a repo on commit `7050a45134e9848fca214ad7e7007e96e5042c03`
+
+  `github.com/Liujingfang1/kustomize//examples/helloWorld?ref=7050a45134e9848fca214ad7e7007e96e5042c03`