fix typo

Author: mirceamironenco

torchtune/modules/kv_cache.py

@@ -17,7 +17,7 @@ class KVCache(nn.Module):
     Args:
         batch_size (int): batch size model will be run with
         max_seq_len (int): maximum sequence length model will be run with
-        num_kv_heads (int): number key/value heads.
+        num_kv_heads (int): number of key/value heads.
         head_dim (int): per-attention head embedding dimension
         dtype (torch.dtype): dtype for the caches
     """