Update MaxText/prefix_cache.py docstring

Co-authored-by: RupengLiu <[email protected]>

MaxText/prefix_cache.py

@@ -142,7 +142,7 @@ def prefix_size_bytes(self) -> int:
     return self._prefix_size_bytes
 
   def clone(self) -> "Value":
-    """Clone to prevent use the same jax array."""
+    """Clone to prevent using the same jax array."""
     copied_prefix = tree_copy(self._prefix)
     return Value(
         prefix=copied_prefix,