Add information about using ratchetFrom on CI systems

[magicus]

Add the important TL;DR from #710 to the documentation where it is pertinent.

I got almost crazy trying to figure out what was wrong. I understand now why ratchetFrom does not work on shallow clones, but as long as #710 is not fixed, this is critical information for anyone trying to setup a way of running Spotless with ratchetFrom on a CI system.

[magicus]

Do you want to have an addition to CHANGES.md for pure documentation updates? I'll fix it, just let me know that it is indeed what you want.

[nedtwigg]

Thanks for the input, no changelog entry needed. You okay with the condensed version I just pushed up?

[magicus]

Personally, I'd rather avoid linking to an issue (which might be edited on a whim by the reporter), and rather "hard code" the solution in place.

But then again, I don't mind much, as long as I can help someone avoid the struggle I had.

[nedtwigg]

Thanks for the feedback. I prefer to link to the issue because it keeps the README easier, and makes it easier to keep up-to-date when new CI systems come to market.