Update IETF-RFC.md

Co-authored-by: Giuseppe Lo Presti <[email protected]>

Author: mickenordin

IETF-RFC.md

@@ -270,7 +270,7 @@ characters.
   to identify the OCM Server of an Invite Receiver.
 
 In Appendix D, an object model is presented as a non-normative guide for
-implementators to understand the relationships between these terms.
+implementers to understand the relationships between these terms.
 
 # General Flow