singleGraph post-processing: added example configuration comments

etc/caseDicts/postProcessing/graphs/sampleDict

-/*--------------------------------*- C++ -*----------------------------------*\
-| =========                 |                                                 |
-| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
-|  \\    /   O peration     | Version:  dev                                   |
-|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
-|    \\/     M anipulation  |                                                 |
-\*---------------------------------------------------------------------------*/
-
-#includeEtc "caseDicts/postProcessing/graphs/sampleDict.cfg"
-
-sets
-(
-    graph
-    {
-        $:setConfig;
-        start   (0   1e-6 0);
-        end     (1   1e-6 0);
-    }
-);
-
-fields          (U p);
-
-// ************************************************************************* //

etc/caseDicts/postProcessing/graphs/sampleDict.cfg

@@ -12,8 +12,8 @@ setFormat   raw;
 
 setConfig
 {
-    type    uniform;
-    axis    distance;
+    type    uniform;   // midPoint, midPointAndFace
+    axis    distance;  // x, y, z, xyz
     nPoints 100;
 }