docs: trace: events.rst: convert some new stuff to ReST format

Some new chapters were added to the documentation. This caused
Sphinx to complain, as the literal blocks there are not properly
tagged as such. Also, a new note added there doesn't follow
the ReST format.

This fixes the following warnings:

    Documentation/trace/events.rst:589: WARNING: Definition list ends without a blank line; unexpected unindent.
    Documentation/trace/events.rst:620: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:623: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:626: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:703: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:697: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:722: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:775: WARNING: Definition list ends without a blank line; unexpected unindent.
    Documentation/trace/events.rst:814: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:817: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:820: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:823: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:826: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:829: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:832: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:844: WARNING: Unexpected indentation.
    Documentation/trace/events.rst:845: WARNING: Block quote ends without a blank line; unexpected unindent.
    Documentation/trace/events.rst:849: WARNING: Unexpected indentation.
    Documentation/trace/events.rst:850: WARNING: Block quote ends without a blank line; unexpected unindent.
    Documentation/trace/events.rst:883: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:886: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:889: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:895: WARNING: Bullet list ends without a blank line; unexpected unindent.
    Documentation/trace/events.rst:895: WARNING: Inline emphasis start-string without end-string.
    Documentation/trace/events.rst:968: WARNING: Inline emphasis start-string without end-string.

Fixes: 34ed6357

 ("tracing: Documentation for in-kernel synthetic event API")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/afbe367ccb7b9abcb9fab7bc5cb5e0686c105a53.1583250595.git.mchehab+huawei@kernel.org


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