ACTION-68: Proposed text for "contextmenu issue"

Regarding: https://www.w3.org/2012/pointerevents/track/actions/68

How about:
"Note that the relative order of these high-level events (click,
contextmenu, focus, blur, etc.) with pointer events is undefined and varies
between user agents."

Perhaps we want to define some term for "high-level" (or "semantic input
events") earlier in the the paragraph as part of Jacob's work to expand it
(and encourage the use of these sorts of events when appropriate).

We could go on with a more concrete example like the following, but I think
it's probably overkill:
"For example, on some user agents contextmenu will often follow a
pointerup, on others it'll often proceed a pointerup or pointercancel, and
in some situations it may be fired without any corresponding pointer event".

Rick