Add documentation re: PYBIND11_DTYPE macro

docs/advanced.rst

@@ -1358,6 +1358,30 @@ template paramenter, and it ensures that non-conforming arguments are converted
 into an array satisfying the specified requirements instead of trying the next
 into an array satisfying the specified requirements instead of trying the next
 function overload.
 function overload.
 
 
+NumPy structured types
+======================
+
+In order for ``py::array_t`` to work with structured (record) types, we first need
+to register the memory layout of the type. This could be done via ``PYBIND11_DTYPE``
+macro which expects the type followed by field names:
+
+.. code-block:: cpp
+
+    struct A {
+        int x;
+        double y;
+    };
+
+    struct B {
+        int z;
+        A a;
+    };
+
+    PYBIND11_DTYPE(A, x, y);
+    PYBIND11_DTYPE(B, z, a);
+
+    /* now both A and B can be used as template arguments to py::array_t */
+
 Vectorizing functions
 Vectorizing functions
 =====================
 =====================