tracing: Fix events.rst section numbering

The in-kernel trace event API should have its own section, and the
duplicate section numbers need fixing as well.

Reported-by: Li Xinhai <lixinhai.lxh@gmail.com>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/90ea854dfb728390b50ddf8a8675238973ee014a.camel@kernel.org


Signed-off-by: Jonathan Corbet <corbet@lwn.net>