perf docs: Fix man page formatting for 'perf lock'

This makes "CONTENTION" a top level section (rather than a subsection of
"INFO").

Fixes: 79079f21f50a501f ("perf lock: Add -k and -F options to 'contention' subcommand")
Reviewed-by: James Clark <[e-mail]>
Signed-off-by: Nick Forrington <[e-mail]>
Tested-by: Ian Rogers <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/Documentation/perf-lock.txt

···
 
 
 CONTENTION OPTIONS
---------------
+------------------
 
 -k::
 --key=<value>::