Is your feature request related to a problem? Please describe.
I think the Validation page has some points that could be enhanced for a better reading experience:

• headers are a little hard to navigate
• some introductory examples have too much information (which distracts from explaining the basics)

Describe the solution you'd like

I'd suggest the following grouping to address both problems pointed out previously.

Overview
Usage
	With Python
		On instantiation
		Lazy validation
	With CLI
Features
	Multiple validators
	Custom messages
	Default and computed values
	Casting / Transform
	Custom conditional expressions
	Inter-related Validation
	Combination Operators
	Selective Validation
Sample examples (longer/full examples moved here)
Reference (actually #validator-parameters)

Note that there are some sub-headings suppressed here. It is part of the proposal to leave sub-headings in the text but suppress them in the table of content menu, which can be achieved by using <h3> tags instead of markdown syntax ###

There are also some renaming of titles, which I understand that may be very personal and subjective.

Describe alternatives you've considered
I haven't considered alternatives.

Additional context
None.