update docs after renaming of PyString -> PyBytes
diff --git a/Doc/c-api/concrete.rst b/Doc/c-api/concrete.rst
index a0dfe21..733a0bc 100644
--- a/Doc/c-api/concrete.rst
+++ b/Doc/c-api/concrete.rst
@@ -65,7 +65,7 @@
 
 .. toctree::
 
-   string.rst
+   bytes.rst
    unicode.rst
    buffer.rst
    tuple.rst