Document remote files in remoteBuild.md (#4624)

* Add file to remote build spec

* Address PR feedback

examples/remoteBuild.md

@@ -1,5 +1,7 @@
 # remote targets
 
+## remote directories
+
 `kustomize build` can be run on a URL. Resources can also reference other
 kustomization directories via URLs too.
 
@@ -24,6 +26,11 @@ SSH clones are also supported either with `[email protected]:owner/repo` or
 
 `file:///` clones are not supported.
 
+## remote files
+Resources can reference remote files via their raw GitHub urls, such
+as `https://raw.githubusercontent.com/kubernetes-sigs/kustomize/8ea501347443c7760217f2c1817c5c60934cf6a5/examples/helloWorld/deployment.yaml`
+.
+
 # Examples
 
 To try this immediately, run a build against the kustomization