STYLE: some general spelling fixes

src/functionObjects/field/fieldAverage/fieldAverage.H

@@ -120,7 +120,7 @@ Usage
 
 
 Note
-    To employ the \c prime2Mean option, the \c mean option must be selecetd.
+    To employ the \c prime2Mean option, the \c mean option must be selected.
 
 See also
     Foam::functionObjects::fvMeshFunctionObject

src/functionObjects/field/fluxSummary/fluxSummary.C

@@ -85,7 +85,7 @@ Foam::word Foam::functionObjects::fluxSummary::checkFlowType
     const word& fieldName
 ) const
 {
-    // Surfaces are multipled by their area, so account for that
+    // Surfaces are multiplied by their area, so account for that
     // in the dimension checking
     const dimensionSet dims =
         (fieldDims * (isSurfaceMode() ? dimTime*dimArea : dimTime));

src/functionObjects/field/surfaceInterpolate/surfaceInterpolate.H

@@ -57,7 +57,7 @@ Usage
     \table
         Property | Description               | Required    | Default value
         type     | type name: nearWallFields | yes         |
-        fields   | list of fields with correspoding output field names | yes |
+        fields   | list of fields with corresponding output field names | yes |
         log      | Log to standard output    | no          | yes
     \endtable