perf tools: Add missing parameters documentation

Add missing documentation for the following parameters:

- perf record -R
- perf report -g

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <1251682323-10395-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index 370344a..59f0b84 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -51,6 +51,16 @@
 	all occurances of this separator in symbol names (and other output)
 	with a '.' character, that thus it's the only non valid separator.
 
+-g [type,min]::
+--call-graph::
+        Display callchains using type and min percent threshold.
+	type can be either:
+	- flat: single column, linear exposure of callchains.
+	- graph: use a graph tree, displaying absolute overhead rates.
+	- fractal: like graph, but displays relative rates. Each branch of
+		 the tree is considered as a new profiled object. +
+	Default: fractal,0.5.
+
 SEE ALSO
 --------
 linkperf:perf-stat[1]