Move examples within bazelbuild/bazel into bazelbuild/examples repository

There is already a folder with bazel examples inside the bazel repository
https://github.com/bazelbuild/bazel/tree/master/examples

It would be good to add in the readme a reference to it and a small sentence explaining what is the difference or why they are separated. It would be nice in the future to have them in a single place and not have them splited between this repo and the bazelbuild/bazel repo.