feat(linter): Format the configuration documentation correctly

The categories section in the documentation is not formatted correctly. This fix aims to correct the formatting.

crates/oxc_linter/src/config/categories.rs

@@ -61,7 +61,7 @@ Configure an entire category of rules all at once.
 
 Rules enabled or disabled this way will be overwritten by individual rules in the `rules` field.
 
-# Example
+Example
 ```json
 {
     "$schema": "./node_modules/oxlint/configuration_schema.json",