[css-view-transitions-2] Rename “Nested View Transitions” to “Nested View Transition Groups”

[bramus]

In View Transitions 2 there is a feature called “Nested View Transitions”. While the feature itself has its value, the term might give authors the wrong idea about what it is actually about: it is not about calling document.startViewTransition from within another document.startViewTransition, but it is about the pseudo trees getting nested.

I think a better name for the feature - one that more clearly conveys the message – is necessary here.

Some candidates:

• “Nested Pseudo Trees”
• “Nested View Transition Groups”
• …

The “Nested View Transition Groups” suggestion from that list is my favorite, as it links back to the view-transition-group property name which is used to enable the behavior.

[fantasai]

This seems editorial, happy to leave it to the editors, but the proposal sgtm. :)