title: Bazel folder naming convention
body: <p>I know that bazel does not impose any specific file structure, but there are some folder naming conventions that are followed by products using Bazel, and some of them (e.g. "third_party") do have a special treatment (it requires the <code>licenses</code> to be specified).</p>
  
  <p>So I don't quite understand the difference between <code>tools</code> and <code>third_party</code>. For example, if I want to put a "ruby toolchain" it's a tool, since it's the language interpreter, but it's also a third_party, because it has been developed by a community. Where should it go?</p>
  
  <p>And what about bazel rules? Where should the be placed idiomatically?</p>