CDT_3: Document `CGAL:Non_planar_plc_facet_exception`

[lrineau]

Issue Details

The intro to the documentation of make_conforming_constrained_Delaunay_triangulation_3 mentions:

In the case where the input contains a non-planar PLC face, building the triangulation may fail with an exception of type CGAL::Non_planar_plc_facet_exception.

• The exception type CGAL::Non_planar_plc_facet_exception should be documented (as derived from std::exception), and
• maybe it should contain non-static data members pointing to the faulty input polygon.

[LOTUS9679]

Hi @lrineau, I see this issue is assigned to you. If you haven't started working on it yet, I would like to contribute by handling the documentation part (Task 1). Would that be okay?