Add doc string to SoFCTransform

Co-authored-by: Benjamin Nauck <benjamin@nauck.se>

src/Gui/Inventor/SoFCTransform.h

@@ -30,6 +30,17 @@
 namespace Gui
 {
 
+/**
+ * @class SoFCTransform
+ * @brief A temporary workaround for coin3d/coin#534.
+ * 
+ * This class is a workaround for a missing feature to reduce the OpenGL stack size.
+ * The issue was reported here: https://github.com/coin3d/coin/issues/534
+ * And was merged here: https://github.com/coin3d/coin/pull/535
+ * 
+ * Once this feature is available in all supported versions of Coin3D, this class should
+ * be removed and all instances should revert to using SoTransform.
+ */
 class GuiExport SoFCTransform : public SoTransform
 {
     using inherited = SoTransform;