STYLE: sampleDict: improved comment

applications/utilities/postProcessing/sampling/sample/sampleDict

@@ -47,12 +47,14 @@ formatOptions
 }
 
 // interpolationScheme. choice of
-//      cell          : use cell-centre value only; constant over cells (default)
+//      cell          : use cell-centre value only; constant over cells
+//                      (default)
 //      cellPoint     : use cell-centre and vertex values
 //      cellPointFace : use cell-centre, vertex and face values.
 //      pointMVC      : use point values only (Mean Value Coordinates)
-//      cellPatchConstrained : use cell-centre except on boundary faces where
-//        it uses the boundary value. For use with e.g. patchCloudSet.
+//      cellPatchConstrained : like 'cell' but uses cell-centre except on
+//                             boundary faces where it uses the boundary value.
+//                             For use with e.g. patchCloudSet.
 // 1] vertex values determined from neighbouring cell-centre values
 // 2] face values determined using the current face interpolation scheme
 //    for the field (linear, gamma, etc.)