add .env.example to kubernetes example

Author: ashleybisram

examples/kubernetes/server/.env.example

@@ -0,0 +1,5 @@
+# This file serves as a template for the .env file you will be creating while following the README steps.
+CHRONOS_GRAFANA_API_KEY=Bearer "<access-token-created-in-step-3-here]>"
+CHRONOS_DB="<MongoDB-or-PostgreSQL>"
+# The URI to the desired MongoDB or PostgreSQL database to save health metrics via Chronos
+CHRONOS_URI="<database-URI-here>"