Add self arguments for __dlpack__ and __dlpack_device__

Author: asmeurer

spec/API_specification/array_object.md

@@ -396,12 +396,16 @@ Converts a zero-dimensional boolean array to a Python `bool` object.
 
 
 (method-__dlpack__)=
-### \_\_dlpack\_\_(*, stream=None)
+### \_\_dlpack\_\_(x, *, stream=None)
 
 Exports the array as a DLPack capsule, for consumption by {ref}`function-from_dlpack`.
 
 #### Parameters
 
+-   **x**: _<array>_
+
+    -   array instance.
+
 -   **stream**: _Optional\[int\]_
 
     -   An optional pointer to a stream, as a Python integer, provided by the consumer that the producer will use to make the array safe to operate on. The pointer is a positive integer. `-1` is a special value that may be used by the consumer to signal "producer must not do any synchronization". Device-specific notes:
@@ -439,10 +443,16 @@ Exports the array as a DLPack capsule, for consumption by {ref}`function-from_dl
 
 
 (method-__dlpack_device__)=
-### \_\_dlpack\_device\_\_()
+### \_\_dlpack\_device\_\_(x, /)
 
 Returns device type and device ID in DLPack format. Meant for use within {ref}`function-from_dlpack`.
 
+#### Parameters
+
+-   **x**: _<array>_
+
+    -   array instance.
+
 #### Returns
 
 -   **device**: _Tuple\[enum.IntEnum, int\]_