perf tools: Reformat record's control fd man text

Adding available control commands in separate paragraph, so it's more
readable and easier to add new commands.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20201216083914.47215-2-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-record.txt

@@ -637,11 +637,17 @@ endif::HAVE_LIBPFM[]
 --control=fifo:ctl-fifo[,ack-fifo]::
 --control=fd:ctl-fd[,ack-fd]::
 ctl-fifo / ack-fifo are opened and used as ctl-fd / ack-fd as follows.
-Listen on ctl-fd descriptor for command to control measurement ('enable': enable events,
-'disable': disable events, 'snapshot': AUX area tracing snapshot). Measurements can be
-started with events disabled using --delay=-1 option. Optionally send control command
-completion ('ack\n') to ack-fd descriptor to synchronize with the controlling process.
-Example of bash shell script to enable and disable events during measurements:
+Listen on ctl-fd descriptor for command to control measurement.
+
+Available commands:
+  'enable'  : enable events
+  'disable' : disable events
+  'snapshot': AUX area tracing snapshot).
+
+Measurements can be started with events disabled using --delay=-1 option. Optionally
+send control command completion ('ack\n') to ack-fd descriptor to synchronize with the
+controlling process.  Example of bash shell script to enable and disable events during
+measurements:
 
  #!/bin/bash