docs: add data-dependent shape admonition

src/array_api_stubs/_draft/manipulation_functions.py

@@ -170,6 +170,11 @@ def repeat(
     """
     Repeats elements of an array.
 
+    .. admonition:: Data-dependent output shape
+        :class: important
+
+        The shape of the output array for this function depend on the data values in the `repeats` array; hence, array libraries which build computation graphs (e.g., JAX, Dask, etc.) may find this function difficult to implement without knowing array values. Accordingly, such libraries may choose to omit this function. See :ref:`data-dependent-output-shapes` section for more details.
+
     Parameters
     ----------
     x: array