PM representative responsibilities added

With regards to the PM meeting [conversation](https://docs.google.com/document/d/1ZElyRqNsGebvMpikEBhSuf2Q6WrEYHB2PgWIlGgwt78/edit?ts=58740b3d#heading=h.1txgejyk87dr), SIG representative functions for the PM group are described.

governance.md

@@ -137,6 +137,13 @@ In order to standardize Special Interest Group efforts, create maximum transpare
 * Participate in release planning meetings and retrospectives, and burndown meetings, as needed
 * Ensure related work happens in a project-owned github org and repository, with code and tests explicitly owned and supported by the SIG, including issue triage, PR reviews, test-failure response, bug fixes, etc. 
 * Use the above forums as the primary means of working, communicating, and collaborating, as opposed to private emails and meetings
+* Represent the SIG for the PM group:
+ * identify all features in the current release from the SIG
+ * track all features (in the repo with all the fields complete)
+ * attend your SIG meetings
+ * attend the PM group meetings
+ * identify the annual roadmap
+ * advise their SIG as needed
 
 # CLA