Clarify current BDS traversal support

README.md

@@ -4,7 +4,7 @@ This repository contains the reference implementation that accompanies the Inter
 
 This reference implementation supports all parameter sets as defined in the Draft at run-time (specified by prefixing the public and private keys with a 32-bit `oid`). Implementations that want to use compile-time parameter sets can remove the `struct xmss_params` function parameter.
 
-_While the behavior of the code in this repository is supposed to be stable, the API is not yet fully complete. In particular, the wrapper for run-time parameters does not yet support the back-end functions that make use of BDS traversal (TODO). We will also add more extensive test functionality, making it easier to compare to other XMSS implementations (TODO)._
+_While the behavior of the code in this repository is supposed to be stable, the API is not yet fully complete. **In particular, the wrapper for run-time parameters does not yet support the back-end functions that make use of BDS traversal. This means that the `xmss_core_fast.c` back-end is somewhat hard to use. This is the most immediate open TODO, and will be resolved soon.**_
 
 _When using the current code base, please be careful, expect changes and watch this document for further documentation._