meta: move to emeritus automatically after 18 months

Similar to the rules for automatic removal from active TSC membership,
provide criteria for automatic assignment to emeritus status for
inactive collaborators.

PR-URL: #41155
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Matteo Collina <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>
Reviewed-By: Antoine du Hamel <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Tobias Nießen <[email protected]>
Reviewed-By: Myles Borins <[email protected]>
Reviewed-By: Filip Skokan <[email protected]>
Reviewed-By: Stewart X Addison <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Danielle Adams <[email protected]>
Reviewed-By: Joyee Cheung <[email protected]>
Reviewed-By: Michael Dawson <[email protected]>
Reviewed-By: Richard Lau <[email protected]>
Reviewed-By: Gus Caplan <[email protected]>

GOVERNANCE.md

@@ -67,6 +67,10 @@ See:
 The TSC can remove inactive collaborators or provide them with _emeritus_
 status. Emeriti may request that the TSC restore them to active status.
 
+A collaborator is automatically made emeritus (and removed from active
+collaborator status) if it has been more than 18 months since the collaborator
+has authored or approved a commit that has landed.
+
 ## Technical Steering Committee
 
 A subset of the collaborators forms the Technical Steering Committee (TSC).