Clarify DOKKU_SCALE usage

refs #1409

[ci skip]

docs/process-management.md

@@ -20,16 +20,16 @@ ps:stop <app>                                   Stop app container(s)
 
 Dokku allows you to run multiple process types at different container counts. For example, if you had an app that contained 1 web app listener and 1 background job processor, dokku can, spin up 1 container for each process type defined in the Procfile. By default we will only start the web process. However, if you wanted 2 job processors running simultaneously, you can modify this behavior in a few ways.
 
-## Include a DOKKU_SCALE file in your repo
+### DOKKU_SCALE file
 
-Dokku expects this file to contain one line for every process defined in your Procfile. Example:
+You can optionally create a `DOKKU_SCALE` file in the root of your repository. Dokku expects this file to contain one line for every process defined in your Procfile. Example:
 ```
 web=1
 worker=2
 ```
 
 
-## Use the ps:scale command. Example:
+### Use the ps:scale command. Example:
 ```
 dokku ps:scale app_name web=1 worker=2
 ```