don't get me wrong, i really like the change but other constraints doesn't follow this example.
most constraints doesn't add examples for default values.

I agree with @timglabisch. In my opinion, the basic examples would be harder to understand if we included the default values for each constraint option.

I disagree: when I began with this topic, I was sad to actually not have any example. Moreover, this ~ is not very helping for those who are looking for exemple(s).

All default values are already documented in the options list. This is a reference documentation, not a beginners guide. If you take a look at book/validation, you'll see enough examples on how to configure constraints and what ~ means.

Should I close this PR then ?

Yes, I think that's the best option here. Anyway, thank you for contributing to the docs, @saro0h. Hope to see you back soon with other improvements.