Fix a syntax issue in Coding Standards

Author: javiereguiluz

Diff for: contributing/code/standards.rst

@@ -211,7 +211,7 @@ Naming Conventions
 * Use `camelCase`_ for PHP variables, function and method names, arguments
   (e.g. ``$acceptableContentTypes``, ``hasSession()``);
 
-Use `snake_case`_ for configuration parameters, route names and Twig template
+* Use `snake_case`_ for configuration parameters, route names and Twig template
   variables (e.g. ``framework.csrf_protection``, ``http_status_code``);
 
 * Use SCREAMING_SNAKE_CASE for constants (e.g. ``InputArgument::IS_ARRAY``);