perf diff: Change default setting to "delta-abs"

The "delta-abs" compute method will show most changed entries on top.
So users can easily see how much effect between the data.  Note that it
also changes the default of -o option to 1 in order to apply the compute
method.  To see original-style (sorted by baseline) use -o 0 option.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170210161856.18422-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/Documentation/perf-diff.txt b/tools/perf/Documentation/perf-diff.txt
index 7391299..66dbe3de 100644
--- a/tools/perf/Documentation/perf-diff.txt
+++ b/tools/perf/Documentation/perf-diff.txt
@@ -87,7 +87,7 @@
 -c::
 --compute::
         Differential computation selection - delta, ratio, wdiff, delta-abs
-        (default is delta).  Default can be changed using diff.compute
+        (default is delta-abs).  Default can be changed using diff.compute
         config option.  See COMPARISON METHODS section for more info.
 
 -p::
@@ -101,7 +101,7 @@
 -o::
 --order::
        Specify compute sorting column number.  0 means sorting by baseline
-       overhead (default) and 1 means sorting by computed value of column 1
+       overhead and 1 (default) means sorting by computed value of column 1
        (data from the first file other base baseline).  Values more than 1
        can be used only if enough data files are provided.
        The default value can be set using the diff.order config option.