Revert "docs: fix bug in examples make target"

This reverts commit 7cb153d8843c5c17c23f324c375c069f1f81eaf2.
Revert "examples: new setup for examples"

This reverts commit 7dbf8768147c6b51a23a3b3d13c40c5070ee6520.
examples: new examples scheme

    - .py example files should go in examples/ in the root of the
      repository
    - they should all be accompanied by an rst file in docs/examples/
      that works through the example explaining all of the steps
    - the matplotlib plot_directive extension should automatically make
      all the plots