Update PSRT inactivity policy (#1911)

Author: StanFromIreland

security/psrt.csv

@@ -15,7 +15,7 @@ Jelle Zijlstra,JelleZijlstra,
 Kushal Das,kushaldas,
 Kirill Podoprigora,eclips4,
 Larry Hastings,larryhastings,
-Łukasz Langa,ambv,Release Manager
+Łukasz Langa,ambv,
 Ned Deily,ned-deily,"Admin, Release Manager"
 Pablo Galindo Salgado,pablogsal,Release Manager
 Paul McMillan,paulmcmillan,

security/psrt.rst

@@ -32,14 +32,19 @@ The nomination succeeds if the nomination receives at least
 two-thirds positive votes from a vote of existing PSRT members
 that is open for one week and not vetoed by the Steering Council.
 
-Once per year the Steering Council will receive a report of inactive members
-of the PSRT with the recommendation to remove the inactive users from the PSRT.
+Every six months the Steering Council will receive a report of inactive PSRT
+members with the recommendation to remove the inactive users from the PSRT.
 “Inactive” is defined as a member who hasn’t coordinated or commented on a
-vulnerability report in the past year since the last report was generated.
+vulnerability report in the past six months since the last report was generated.
 The Steering Council may remove members of the PSRT with a simple vote.
 
-Members of the PSRT who are a Release Manager or Steering Council member may
-remain in the PSRT regardless of inactivity in vulnerability reports.
+Release Managers must be members of the PSRT for the duration of their term.
+Steering Council members and the release team experts may join the PSRT if they
+wish. All of these members may remain in the PSRT regardless of inactivity in
+vulnerability reports. When a member leaves these roles, their PSRT membership
+becomes a regular membership subject to the inactivity policy above.
+PSRT admins are not exempt from the inactivity policy and are included in the
+report of inactive members.
 
 .. _similar to core team nominations: https://devguide.python.org/core-team/join-team/