Documentation

This is w.r.t the issue#143804

It was pointed out it is not a bug (agreed) but we can improve the documentation of this module
since it is now not very clear that

• Onehas to over-ride "emptyline" so that the last line is not repeated
• Onehas to over-ride do_EOF to quit cleanly

A tutorial on this in the documentation would be helpful as right now these are at the level of method level documentation and quite unclear at the usage level.