document bootstrap version on example(s)

enhancment for the examples:

https://intercoolerjs.org/examples/inlinevalidation.html

Please add wich version of boostrap is used (probably applies to all examples).

Bootstrap v4.1.0 is working with `is-valid` and `is-invalid` and therefore the example doesn't work if you copy-paste it

Solution for 4.10:
On the input field the class `is-valid` or `is-invalid` should be added to show the message, else it doesn't show the message.

thnks