add documentation for t8_forest_leaf_face_neighbors_ext

src/t8_forest/t8_forest_general.h

@@ -571,6 +571,11 @@ t8_forest_leaf_face_neighbors (t8_forest_t forest, t8_locidx_t ltreeid, const t8
                                t8_locidx_t **pelement_indices, t8_eclass_scheme_c **pneigh_scheme,
                                int forest_is_balanced);
 
+/** Like \ref t8_forest_leaf_face_neighbors but also provides information about the global neighbors and the orientation. 
+  * \param [out]   gneigh_tree  The global tree IDs of the neighbor trees.
+  * \param [out]   orientation  The face orientation is computed and stored there.
+  * All other parameters and behavior are identical to \ref `t8_forest_leaf_face_neighbors`.
+  */
 void
 t8_forest_leaf_face_neighbors_ext (t8_forest_t forest, t8_locidx_t ltreeid, const t8_element_t *leaf,
                                    t8_element_t **pneighbor_leaves[], int face, int *dual_faces[], int *num_neighbors,