Add rcon client to container

docker/files/players-online.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+PLAYERS=$(docker exec xenodochial_spence rcon /players)
+ONLINE_COUNT=$(echo "$PLAYERS" | grep -c " (online)$")
+
+if [[ "$ONLINE_COUNT" -gt "0" ]]; then
+    echo "$PLAYERS"
+    # exit with 75 (EX_TEMPFAIL) for watchtower
+    # https://containrrr.dev/watchtower/lifecycle-hooks/
+    exit 75
+fi