ENH: [surface|vol]FieldValue - added name of weight field to output file header if used

src/functionObjects/field/fieldValues/surfaceFieldValue/surfaceFieldValue.C

@@ -560,6 +560,11 @@ void Foam::functionObjects::fieldValues::surfaceFieldValue::writeFileHeader
         writeHeaderValue(os, "Area", totalArea_);
         writeHeaderValue(os, "Scale factor", scaleFactor_);
 
+        if (weightFieldName_ != "none")
+        {
+            writeHeaderValue(os, "Weight field", weightFieldName_);
+        }
+
         writeCommented(os, "Time");
         if (writeArea_)
         {

src/functionObjects/field/fieldValues/volFieldValue/volFieldValue.C

@@ -93,6 +93,10 @@ void Foam::functionObjects::fieldValues::volFieldValue::writeFileHeader
 ) const
 {
     volRegion::writeFileHeader(*this, os);
+    if (weightFieldName_ != "none")
+    {
+        writeHeaderValue(os, "Weight field", weightFieldName_);
+    }
 
     writeCommented(os, "Time");