update unstable prefix

proposals/2883-mls.md

@@ -1,6 +1,6 @@
 # MSC2883: [WIP] Matrix-flavoured MLS
 
-[Messaging Layer Security (MLS)](https://messaginglayersecurity.rocks/) is
+[Messaging Layer Security (MLS)](https://messaginglayersecurity.rocks/) is an
 [IETF standard](https://datatracker.ietf.org/doc/rfc9420/) for end-to-end
 encryption in group chats.  [Decentralised
 MLS](https://gitlab.matrix.org/matrix-org/mls-ts/-/blob/decentralised2/decentralised.org)
@@ -302,5 +302,8 @@ InitKey, which maps over to fallback OTKs.\]
 
 ## Unstable prefix
 
-Implementations should use the prefix `org.matrix.msc2883.v0.dmls` in place of
+Implementations should use the prefix `org.matrix.msc2883.v1.dmls` in place of
 `m.dmls.v1` until this lands in a released version of the specification.
+
+The prefix `org.matrix.msc2883.v0.dmls` was used in implementations based on a
+draft version of MLS.