Please add a description for fuzzer output columns

[fmstephe]

There are two columns whose meaning are unclear to me.

Cover - this is not a percent value, so a description would help to interpret this.

Restarts - it’s unclear to me what causes the fuzzer to restart. There is an indication that you should aim to restart 1/1000 but it’s not clear how to influence this.

[josharian]

Yes, we should document these in the readme.

I actually think we shouldn’t display restarts at all, but instead monitor them and print a warning on stderr as needed; the warning could explain the problem more fully.

[dvyukov]

I agree restarts is not very useful as is. Cover percent is quite hard to do in a meaningful way. Ideally we need to understand what's potentially coverable and use it as max. But this is non-trivial to do. And it we do percent out of all linked in code, then the percent will be sadly small and won't be meangful anyway.

[fmstephe]

For myself I would be happy with any reasonable, and rough, description of coverage. It doesn't need to be a percentage value. But since it isn't it would be nice to have an idea of what this ever increasing number actually is.