add script + doc to change a user to admin

roles/matrix-server/templates/usr-local-bin/matrix-make-user-admin.j2

@@ -0,0 +1,15 @@
+#!/bin/bash
+
+if [ $# -ne 1 ]; then
+        echo "Usage: "$0" <username>"
+        exit 1
+fi
+
+docker run \
+        -it \
+        --rm \
+        --env-file={{ matrix_environment_variables_data_path }}/env-postgres-pgsql-docker \
+        --network {{ matrix_docker_network }} \
+        {{ matrix_postgres_docker_image_to_use }} \
+        psql -h {{ matrix_postgres_connection_hostname }} -c "UPDATE users set admin=1 WHERE name like '@$1:{{ host_specific_hostname_identity }}'"
+