adding example dictionary for particleTracks

applications/utilities/postProcessing/lagrangian/particleTracks/particleTrackProperties

+/*--------------------------------*- C++ -*----------------------------------*\
+| =========                 |                                                 |
+| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
+|  \\    /   O peration     | Version:  1.5.x                                 |
+|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
+|    \\/     M anipulation  |                                                 |
+\*---------------------------------------------------------------------------*/
+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       dictionary;
+    location    "constant";
+    object      particleTrackProperties;
+}
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+cloudName       reactingCloud1;
+
+sampleFrequency 1;
+
+maxPositions    1000000;
+
+
+// ************************************************************************* //