Fix aiBone.mOffsetMatrix documentation

Fixed the comment on the `mOffsetMatrix` property to be correct.
See https://assimp-docs.readthedocs.io/en/latest/API/API-Documentation.html#_CPPv46aiBone
See also https://stackoverflow.com/a/73603994

include/assimp/mesh.h

@@ -281,7 +281,7 @@ struct aiBone {
     //! The influence weights of this bone, by vertex index.
     C_STRUCT aiVertexWeight *mWeights;
 
-    /** Matrix that transforms from bone space to mesh space in bind pose.
+    /** Matrix that transforms from mesh space to bone space in bind pose.
      *
      * This matrix describes the position of the mesh
      * in the local space of this bone when the skeleton was bound.