Yes. Fixing up documentation is always helpful, even if it’s a one letter change!
Now, updating “copyright 2018-2019” to “2020” isn’t.
Now, updating “copyright 2018-2019” to “2020” isn’t.
Unfortunately, in many cases now, copyright is based on the year the author died, rather than the year the work was created, which means it is much harder to work out if something has entered the public domain.
Changing the date without changing the code significantly is arguably fraudulent.
if you create some content in 2018 and I rip it off in 2019 and then you update your copyright to 2020, what's to stop me from saying I came up with it first?
In some countries the publishing date is what counts, and they define publishing for websites as when the site was viewed.
No, the publishing date is relevant (not the first publishing date).
I regularly have to shop around for libraries. Seeing a copyright 2017 doesn't bode well for the documentation or the project being maintained.