Expand documentation to include InspectorControls code examples

[danielbachhuber]

I'm working on a demo ES5 Countdown Timer block at the moment. It needs two control elements: label and countdown_date.

Because the latter is a computed value, I want to create a TextControl (or similar) to input the date. However, only BlockControls are documented so I spent a fair amount of time in confusion until I realized there's an InspectorControls API too. It would be nice to have this documented.

[chrisvanpatten]

This should be an easy one — we have the documentation already, just need some code examples.

https://github.com/WordPress/gutenberg/blob/master/docs/blocks/block-controls-toolbars-and-inspector.md

Possibly volunteering @ajitbohra for this one, if you're interested? 😅

[ajitbohra]

@chrisvanpatten will do documentation sprint in the next couple of day will add this to my list.

Seems like probably have worked on this but forget to push!