Update configuration.md

Fix typo in YAML_CONFIG_FILENAME

Author: M3sca

content/techniques/configuration.md

@@ -148,7 +148,7 @@ import { readFileSync } from 'fs';
 import * as yaml from 'js-yaml';
 import { join } from 'path';
 
-const YAML_CONFIG_FILENAME = 'config.yml';
+const YAML_CONFIG_FILENAME = 'config.yaml';
 
 export default () => {
   return yaml.load(