fix: address YAML lint issues

- Fix comment indentation in prometheus.yml
- Fix empty values in docker-compose volumes sections
- All pre-commit hooks now pass

Author: benjisho

docker-compose.test.yml

@@ -85,8 +85,8 @@ services:
       - GF_USERS_ALLOW_SIGN_UP=false
 
 volumes:
-  prometheus_data:
-  grafana_data:
+  prometheus_data: {}
+  grafana_data: {}
 
 networks:
   nginx-monitoring:

docker-compose.yml

@@ -85,8 +85,8 @@ services:
       - GF_USERS_ALLOW_SIGN_UP=false
 
 volumes:
-  prometheus_data:
-  grafana_data:
+  prometheus_data: {}
+  grafana_data: {}
 
 networks:
   nginx-monitoring:

examples/docker-compose/prometheus/prometheus.yml

@@ -3,8 +3,8 @@ global:
   evaluation_interval: 15s
 
 rule_files: []
-  # - "first_rules.yml"
-  # - "second_rules.yml"
+# - "first_rules.yml"
+# - "second_rules.yml"
 
 scrape_configs:
   # The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.