Buffers are not sequence objects (!). Put them in the abstract objects layers
instead.
diff --git a/Doc/c-api/abstract.rst b/Doc/c-api/abstract.rst
index db4c02a..ad53881 100644
--- a/Doc/c-api/abstract.rst
+++ b/Doc/c-api/abstract.rst
@@ -22,4 +22,5 @@
    sequence.rst
    mapping.rst
    iter.rst
+   buffer.rst
    objbuffer.rst