Eliminate the mostly obsolete `Public API` sub-section from the
`Trace2 API` section in the documentation. Strengthen the referral
to `trace2.h`.
Most of the technical information in this sub-section was moved to
`trace2.h` in 6c51cb525d (trace2: move doc to trace2.h, 2019-11-17) to
be adjacent to the function prototypes. The remaining text wasn't
that useful by itself.
Furthermore, the text would need a bit of overhaul to add routines
that do not immediately generate a message, such as stopwatch timers.
So it seemed simpler to just get rid of it.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
8e8c5ad27a