docs(example): move config.yaml to config folder (#265)

ref: https://github.com/TwiN/gatus/issues/151#issuecomment-912932934

update all exmaple in docker-compose file.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

.examples/docker-compose-grafana-prometheus/docker-compose.yml

@@ -7,7 +7,7 @@ services:
     ports:
       - "8080:8080"
     volumes:
-      - ./config.yaml:/config/config.yaml
+      - ./config:/config
     networks:
       - metrics