docs: Explain --fail-early does not imply --fail

[jay]

I made a mistake in some scripts replacing --fail with --fail-early, not remembering the latter doesn't imply the former. You'd think I would know since it looks like I may have been one of the initial reviewers but I don't remember it.

For example I get a bunch of files using --fail-early --location --remote-name-all and they were all written even though one had failed. I think it's an easy mistake to make, and so it should be documented that it's for transfer errors and does not imply --fail but can be combined with it.

Not in this commit:
The short help could be modified as well, but it may be overkill?

 -f, --fail          Fail silently (no output at all) on HTTP errors (H)
     --fail-early    Fail and exit on first transfer error; can use with --fail

[bagder]

I'm 👍 on the main change, but I'm not too fond of the short help suggestion. I think that area is just too tight to make it make sense. "can use with --fail" doesn't really explain it.

[jay]

Ok, thanks for the review.