externalWallHeatFluxTemperature: Correct doc

Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=1745

src/TurbulenceModels/compressible/turbulentFluidThermoModels/derivedFvPatchFields/externalWallHeatFluxTemperature/externalWallHeatFluxTemperatureFvPatchScalarField.H

@@ -60,7 +60,7 @@ Description
         thicknessLayers | list of thicknesses per layer [m] | yes |
         kappaLayers  | list of thermal conductivites per layer [W/m/K] | yes |
         kappaName    | name of thermal conductivity field | yes  |
-        QrName       | name of the radiative field | no | no
+        Qr           | name of the radiative field | no | no
         relaxation   | relaxation factor for radiative field | no | 1
     \endtable
 
@@ -77,7 +77,7 @@ Description
         kappaLayers     (1 2 3 4);
         value           uniform 300.0;
         kappaName       none;
-        QrName          none;
+        Qr              none;
         relaxation      1;
     }
     \endverbatim