Make readme clearer (#132)

Author: edwardhorsford

app/guide/how-to-add-a-new-service.md

@@ -10,14 +10,15 @@ Posts in this design history are grouped by the service or team they relate to.
 
 You may want to [look at an existing pull request](https://github.com/NHSDigital/prevention-services-design-history/pull/20) to see the files you need to update.
 
-You will need to create some files and folders based on the name of your service, using lowercase and hypens. For example, for `Manage breast screening` you would use `manage-breast-screening`
+You will need to create some files and folders based on the name of your service, using lowercase and hypens. For example, for `Manage breast screening` you would use `manage-breast-screening`.
 
 You’ll need to:
 
 * create a Markdown file in `app/posts/`, for example `app/posts/your-service-name.md`. Copy an existing example and update any references to match your service.
-* create a folder for your service in `app/images/`, for example `app/images/your-service-name/`
-* create a folder for your service in `app/posts/`, for example `app/posts/your-service-name/`
+* create a folder for your service in `app/images/`, for example `app/images/your-service-name/`.
+* create a folder for your service in `app/posts/`, for example `app/posts/your-service-name/`.
 * inside your service’s post folder, ceate a json file `your-service-name.json`, for exampole `app/posts/your-service-name/your-service-name.json`. Copy an existing example for what to put in it.
-* update `eleventy.config.js` to create a new 'collection' for your service (copy one of the existing examples)
-* update `app/_layouts/_product.njk` to list your new service in the sections variable
-* open a pull request with your changes
+* update `eleventy.config.js` to create a new 'collection' for your service (copy one of the existing examples).
+* update `app/_layouts/_product.njk` to list your new service in the sections variable.
+* **note:** you will need to [add a post](/guide/how-to-publish/) before the service can be found in the navigation.
+* open a pull request with your changes.