Simplify MLS references

draft-ietf-sframe-enc.md

@@ -775,7 +775,7 @@ they are removed), then the sender will need to distribute a new sender key.
 ## MLS
 
 The Messaging Layer Security (MLS) protocol provides group authenticated key
-exchange {{?MLS-ARCH=I-D.ietf-mls-architecture}} {{!MLS-PROTO=RFC9420}}.  In
+exchange {{?I-D.ietf-mls-architecture}} {{!RFC9420}}.  In
 principle, it could be used to instantiate the sender key scheme above, but it
 can also be used more efficiently directly.
 
@@ -1043,7 +1043,7 @@ The registration template is as follows:
 
 * Recommended: Whether support for this cipher suite is recommended by the IETF.
   Valid values are "Y", "N", and "D" as described in {{Section 17.1 of
-  MLS-PROTO}}. The default value of the "Recommended" column is "N". Setting the
+  RFC9420}}. The default value of the "Recommended" column is "N". Setting the
   Recommended item to "Y" or "D", or changing an item whose current value is "Y"
   or "D", requires Standards Action {{RFC8126}}.