Add detailed description to DLPackCreationError exception

Author: antonwolfy

doc/reference/exceptions.rst

@@ -11,4 +11,27 @@ specific, such as linear algebra errors.
 Exceptions
 ----------
 
-.. autodata:: DLPackCreationError
+.. data:: AxisError
+
+    Given when an axis is invalid.
+
+.. data:: DLPackCreationError
+
+    Given when constructing DLPack capsule from either :class:`dpnp.ndarray` or
+    :class:`dpctl.tensor.usm_ndarray` based on a USM allocation
+    on a partitioned SYCL device.
+
+    .. rubric:: Examples
+
+    .. code-block:: python
+
+        >>> import dpnp as np
+        >>> import dpctl
+        >>> dev = dpctl.SyclDevice('cpu')
+        >>> sdevs = dev.create_sub_devices(partition=[1, 1])
+        >>> q = dpctl.SyclQueue(sdevs[0])
+        >>> x = np.ones(10, sycl_queue=q)
+        >>> np.from_dlpack(x)
+        Traceback (most recent call last):
+        ...
+        DLPackCreationError: to_dlpack_capsule: DLPack can only export arrays based on USM allocations bound to a default platform SYCL context