chore: update Admin WG policy and member (#550)

* chore: update Admin WG policy and member

This PR contains one key policy change (namely that Admin WG members can participate in other working groups, but cannot chair those groups) that requires approval from all of the current working groups:
@electron/wg-api @electron/wg-community-safety @electron/wg-ecosystem @electron/wg-infra @electron/wg-outreach @electron/wg-releases @electron/wg-security @electron/wg-upgrades

* Update wg-administrative/README.md

Co-authored-by: Mark Lee <malept@users.noreply.github.com>

wg-administrative/README.md

@@ -4,15 +4,15 @@ The Administrative Working Group (AWG) oversees the entire governance and projec
 
 AWG members should consist of folks who manage a substantial investment in the project.
 To avoid the AWG becoming the _superpower_ group,
-members should not participate in other technical working groups.
+members should not chair other technical working groups.
 The initial group members consist of management from Microsoft, and Slack whose teams contain full-time Electron contributors.
 
 ## Membership
 
 | Avatar | Name | Role | Time Zone |
 | -------------------------------------------|----------------------|----------------------------| -------- |
 | <img src="https://github.com/PlaineKevin.png" width=100 alt="@PlaineKevin">  | Kevin Nguyen [@PlaineKevin](https://github.com/PlaineKevin) | Chair | PT (Los Angeles) |
-| <img src="https://github.com/groundwater.png" width=100 alt="@groundwater">  | Jacob Groundwater [@groundwater](https://github.com/groundwater) | Member | PT (San Francisco) |
+| <img src="https://github.com/jkleinsc.png" width=100 alt="@jkleinsc">  | John Kleinschmidt [@jkleinsc](https://github.com/jkleinsc) | Member | EST (Harrisburg) |
 
 ## Areas of Responsibility