slack-config: Archive lokomotive channel

We have archived the lokomotive repository already, more info here:
	kinvolk/lokomotive#1582 (comment)

I've talked with the Lokomotive team at Microsoft and we decided to
archive the slack channel too, as we don't plan to continue developing
the project.

Signed-off-by: Rodrigo Campos <[email protected]>

Author: rata

communication/slack-config/channels.yaml

@@ -309,6 +309,7 @@ channels:
   - name: litmus
   - name: litmus-dev
   - name: lokomotive
+    archived: true
   - name: magnum-cluster-api
   - name: malaysia-users
   - name: malta-users