Update docs for per product control files

Author: Mab879

docs/manual/developer/03_creating_content.md

@@ -837,6 +837,8 @@ controls:
        - systemd_target_multi_user
 ```
 
+Control files that apply to multiple products should be stored in `controls` folder in the root of the project.
+If the control file is only applicable to one product it should be store in the `controls` directory under the products folder.
 
 ### Defining levels
 

docs/manual/developer/04_style_guide.md

@@ -317,7 +317,8 @@ Benchmark sections must be in the following order, if they are present.
 
 ### Controls
 
-These rules apply to the files in `controls/`.
+These rules apply to the files in `controls/` and `products/*/controls`.
+Product specific controls should be stored under the respective controls directory.
 All the above [YAML](#yaml) rules apply.
 
 #### Control Sections