slack: Add Release Managers usergroup

Signed-off-by: Stephen Augustus <saugustus@vmware.com>

communication/slack-config/usergroups.yaml

@@ -1,6 +1,23 @@
 # This file contains a list of all Slack usergroups that exist.
 
 usergroups:
+  - name: release-managers
+    long_name: Release Managers
+    description: Release Managers. Ping for questions on branch cuts and building/packaging Kubernetes.
+    channels:
+      - release-managers
+      - sig-release
+    members:
+      - aleksandra-malinowska
+      - bubblemelon
+      - calebamiles
+      - feiskyer
+      - hoegaarden
+      - idealhack
+      - justaugustus
+      - listx
+      - sumitranr
+      - tpepper
   - name: test-infra-oncall
     external: true
   - name: youtube-admins
@@ -27,4 +44,4 @@ usergroups:
       - paris
       - castrojo
       - mrbobbytables
-      - alejandrox1
+      - alejandrox1

communication/slack-config/users.yaml

@@ -2,12 +2,22 @@
 # usernames to Kubernetes Slack user IDs.
 users:
   alejandrox1: U6AS37R50
+  aleksandra-malinowska: U357LUPHS
+  bubblemelon: U7K9C643G
+  calebamiles: U1ZDD4CUR
   castrojo: U1W1Q6PRQ
+  feiskyer: U0ASA4398
+  hoegaarden: U7VA4RZS9
+  idealhack: U5NJ3DQM9
   idvoretskyi: U0CBHE6GM
   jbeda: U09QZ63DX
   jdumars: U0YJS6LHL
   jeefy: U5MCFK468
+  justaugustus: U0E0E78AK
   katharine: UBTBNJ6GL
+  listx: UFCU8S8P3
   mrbobbytables: U511ZSKHD
   paris: U5SB22BBQ
-  sarahnovotny: U0AGW7007
+  sarahnovotny: U0AGW7007
+  sumitranr: UCQN13L9H
+  tpepper: U6UB5V4TX