title: Kubernetes: make pod directory writable
body: <p>I have docker image with config folder in it.
  Logback.xml is located there.
  So I want to have ability to change logback.xml in pod (to up log level dinamicly, for example)
  First, I've thought to use epmtyDir volume, but this thing rewrite directory and it becomes empty.
  So Is there some simple method to make directory writable into pod?</p>