wip

Author: lucasmcdonald3

README.rst

@@ -451,7 +451,7 @@ sharing entries in that cache across threads needs to be done carefully
 
 **Important:** Components from the `AWS Cryptographic Material Providers Library (MPL)`_
 have separate thread safety considerations.
-For more information, see the note on thread safety in that project's README.
+For more information, see the note on thread safety in that project's README (TODO-MPL: link)
 
 
 .. _AWS Encryption SDK: https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/introduction.html