docs/porting.rst: pybind11 vs nanobind comparisons via litgen doc

docs/porting.rst

@@ -358,3 +358,12 @@ Bullet points marked with ● may be reintroduced eventually, but this will
 need to be done in a careful opt-in manner that does not affect code
 complexity, binary size, and compilation/runtime performance of basic bindings
 that don't depend on these features.
+
+Examples
+----------------
+
+The documentation for `litgen <https://pthom.github.io/litgen>`_ includes a 
+series of examples with side-by-side comparisons of pybind11 and nanobind 
+binding code. For instance, see the section on 
+`classes <https://pthom.github.io/litgen/litgen_book/06_05_00_classes.html>`_ 
+for a practical look at these differences.