perf config: Document variables for 'colors' section in man page

Explain 'colors' section and its variables, used for The variables for
customizing the colors used in the output for the 'report', 'top' and
'annotate' in the TUI, those are:

'top', 'medium', 'normal', 'selected',
'jump_arrows', 'addr' and 'root'.
Signed-off-by: NTaeung Song <treeze.taeung@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1452253193-30502-2-git-send-email-treeze.taeung@gmail.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-config.txt

@@ -98,6 +98,52 @@ Given a $HOME/.perfconfig like this:
 		order = caller
 		sort-key = function
 
+Variables
+~~~~~~~~~
+
+colors.*::
+	The variables for customizing the colors used in the output for the
+	'report', 'top' and 'annotate' in the TUI. They should specify the
+	foreground and background colors, separated by a comma, for example:
+
+		medium = green, lightgray
+
+	If you want to use the color configured for you terminal, just leave it
+	as 'default', for example:
+
+		medium = default, lightgray
+
+	Available colors:
+	red, yellow, green, cyan, gray, black, blue,
+	white, default, magenta, lightgray
+
+	colors.top::
+		'top' means a overhead percentage which is more than 5%.
+		And values of this variable specify percentage colors.
+		Basic key values are foreground-color 'red' and
+		background-color 'default'.
+	colors.medium::
+		'medium' means a overhead percentage which has more than 0.5%.
+		Default values are 'green' and 'default'.
+	colors.normal::
+		'normal' means the rest of overhead percentages
+		except 'top', 'medium', 'selected'.
+		Default values are 'lightgray' and 'default'.
+	colors.selected::
+		This selects the colors for the current entry in a list of entries
+		from sub-commands (top, report, annotate).
+		Default values are 'black' and 'lightgray'.
+	colors.jump_arrows::
+		Colors for jump arrows on assembly code listings
+		such as 'jns', 'jmp', 'jane', etc.
+		Default values are 'blue', 'default'.
+	colors.addr::
+		This selects colors for addresses from 'annotate'.
+		Default values are 'magenta', 'default'.
+	colors.root::
+		Colors for headers in the output of a sub-commands (top, report).
+		Default values are 'white', 'blue'.
+
 SEE ALSO
 --------
 linkperf:perf[1]