I'll also update the README.md in a second pass.

That way they will be automatically included in the base outrigger
image as examples/elastic-newstracker/*.juttle.

Update the instructions to assume the in-container examples that are
now provided by the base outrigger container. I'm going to add an
examples/README.md that talks about the in-container examples and how
you can map over them by docker volume mapping instructions.

Add a top-level README.md that talks about how we use docker-compose
to run an outrigger and linked backend containers and map a config
file in juttle-config.json into the outrigger container. This also
contains a known problems section with some gotchas I ran into.

Also add a top level index.juttle that points into the various
subdirectories.

This required changing how we copy files into the container so we only
copy the juttle files and not everything.

Rework the various READMEs to assume the above docker-compose
instance. They now only talk about any additional .yml file necessary,
any additions to juttle-config.json, and describe the juttle programs.

In a later PR, I'll try to tackle the problem of elasticsearch always
being populated from scratch every time you run docker-compose
run. This is in pretty good shape now so I'd like to get it merged.