nit

Author: crusaderky

array_api_compat/common/_helpers.py

@@ -886,8 +886,12 @@ class at:
 
     Caveat
     ------
-    The behaviour of methods other than `get()` when the index is an array of
-    integers which contains multiple occurrences of the same index is undefined.
+    Sparse does not support update methods yet.
+
+    Caveat
+    ------
+    The behaviour of update methods when the index is an array of integers which
+    contains multiple occurrences of the same index is undefined.
 
     **Undefined behaviour:** ``at(x, [0, 0]).set(2)``