Remove redundant shapes from pooling docstrings

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 8a255805-976d-4261-b430-561adafb3cc6

src/colipri/pooling.py

@@ -14,9 +14,8 @@ def _get_valid_token_mask(
     """Get a validated Boolean mask for valid sequence positions.
 
     Args:
-        sequence: Sequence embeddings with shape `(batch, length, embed_dim)`.
-        attention_mask: Mask with shape `(batch, length)`, where nonzero entries
-            identify valid positions.
+        sequence: Sequence embeddings.
+        attention_mask: Mask where nonzero entries identify valid positions.
 
     Returns:
         A Boolean mask on the sequence device, or `None` when no mask is provided.