DOC: Avoid documenting ivar default values in SpatialFunction class

Avoid documenting ivar default values in
`itk::ConicShellInteriorExteriorSpatialFunction` since:
- All ivar values should be initialized to some default value.
- When default values are changed, it is easy to forget about updating
  the documentation and making it inconsistent with the actual value in
  the code.

Author: jhlegarreta

Modules/Core/Common/include/itkConicShellInteriorExteriorSpatialFunction.h

@@ -115,7 +115,7 @@ class ITK_TEMPLATE_EXPORT ConicShellInteriorExteriorSpatialFunction
 
   /** Set/Get direction along the gradient to search.
    * Set to true to use the direction that the gradient is pointing;
-   * set to false for the opposite direction. Default is Off. */
+   * set to false for the opposite direction. */
   itkGetConstMacro(Polarity, bool);
   itkSetMacro(Polarity, bool);
   itkBooleanMacro(Polarity);