The existence of a manager establishes a liaison

This small changes clarifies that the only formal process to establish a "formal liaison relationship" is the appointment of a liaison manager. This is already explain like this in the introduction and this change aligns the text better.

Author: mirjak

draft-iab-rfc4052bis.md

@@ -142,7 +142,7 @@ This version of the document contains the following updates:
 
 # Establishing Formal Liaison Relationships {#relationship}
 
-A formal liaison relationship is established between the IETF and
+The IAB appoints a liaison manager to establish a formal liaison relationship between the IETF and
 another organization when it is mutually agreeable and beneficial to do so.
 
 Generally informal collaboration between the IETF and peer