- 🇬🇧United Kingdom catch
#151 added hook documentation, but #156 doesn't.
I'm also a bit confused why we need an alter hook as opposed to a module or site adding its own date formats. Is it for when someone is using a hard-coded custom format instead of a configured date format? But in that case, an issue against the contrib module might be better.
Tagging for issue summary update for the above.