v.io/v23/uniqueid:  Comment reason for not using a verror error.
v.io/v23/uniqueid:  Comment reason for not using a verror error.

I'm trying to make all of (non-test) v.io/v23 use verror instead of fmt.Errorf.

I can't do that in uniqueid because Go's conflation of package interfaces and
implementations means it can't cope with the import cycle (vtrace, uniqueid,
verror).  (The interfaces have no cycles, and thus a different language would
have had no trouble.)

I'm just commenting the reason here, so future maintainers don't go down the
same road again and again.

Better suggestions welcome.

Change-Id: I49690903f808c924b3b1e6a682a1b79c5e264cbb

vanadium/go.v23,vanadium/go.v23,vanadium/go.v23