[UX] `post_run_summary` should indicate it did something

[eddiebergman]

If you run python -m neps_examples.basic_usage.hyperparameters, youll get a log that NePs ran.
Now what?

It's not clear that anything was written to disk or where it was written to. If you run the example again, you essentially just get this:

INFO:neps:Starting neps.run using root directory results/hyperparameters_example
INFO:neps:Running bayesian_optimization as the searcher
INFO:neps:Algorithm: bayesian_optimization

INFO:neps:Maximum total evaluations is reached, shutting down

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Ideally we should indicate that post_run_summary writes a file somewhere and even more ideally, at the end of execution, indicate what was saved/stored/ran.