Validate JSON matches expected schema

It doesn’t take much digging to figure out the docs have this completely wrong.

@Jass @duyluong Before this PoC/feature gains too much traction and invites users to completely misinterpret its intent and purpose, please understand the difference (highlighted by @anon46315158) and fix the documentation.

If one of us (few) were around 5+ years ago to advise you, the mismatch between WebUI.setText and WebUI.getText (dare I mention WebUI.getAttribute?) wouldn’t have happened. Let’s nip this one in the bud while we have a chance PLEASE!