STYLE: add usage notes

executables/cartesian2DMesh/cartesian2DMesh.C

executables/cartesianMesh/cartesianMesh.C

executables/pMesh/pMesh.C

executables/tetMesh/tetMesh.C

utilities/FLMAToSurface/FLMAToSurface.C

utilities/FMSToSurface/FMSToSurface.C

utilities/FMSToVTK/FMSToVTK.C

utilities/checkSurfaceMesh/checkSurfaceMesh.C

utilities/copySurfaceParts/copySurfaceParts.C

...ies/extrudeEdgesInto2DSurface/extrudeEdgesInto2DSurface.C

utilities/generateBoundaryLayers/generateBoundaryLayers.C

utilities/importSurfaceAsSubset/importSurfaceAsSubset.C

utilities/improveMeshQuality/improveMeshQuality.C

utilities/improveSymmetryPlanes/improveSymmetryPlanes.C

utilities/mergeSurfacePatches/mergeSurfacePatches.C

utilities/meshToFPMA/meshToFPMA.C

utilities/patchesToSubsets/patchesToSubsets.C

utilities/preparePar/preparePar.C

utilities/removeSurfaceFacets/removeSurfaceFacets.C

utilities/scaleMesh/scaleMesh.C