To an average user, it may be unclear why these notes are not just in
the reference trace; that's because they are more important, because
they are inline calls through which comptime values may propagate. There
are now 3 possible wordings for this note:

* "called at comptime here"
* "called inline here"
* "generic function instantiated here"

An alternative could be these wordings:

* "while analyzing comptime call here"
* "while analyzing inline call here"
* "while analyzing generic instantiation here"

I'm not sure which is better -- but this commit is certainly better than
status quo.