update prototype guidance

docs/components/install-nhsapp-frontend-in-your-prototype.md

@@ -29,6 +29,85 @@ Enter
 npm install --save nhsapp-frontend
 ```
 
+## Step 3
+
+In your HTML editor, open
+
+```sh
+/app/assets/sass/application.scss
+```
+
+After
+
+```sh
+// Import NHS.UK frontend library
+@import 'node_modules/nhsuk-frontend/packages/nhsuk';
+```
+
+Paste
+
+```sh
+// Import all styles from the NHS App frontend library
+@import 'node_modules/nhsapp-frontend/dist/nhsapp/all';
+```
+
+## Step 4
+
+In your root folder, open
+
+```sh
+/app.js
+```
+
+and find
+
+```sh
+appViews
+```
+
+After
+
+```sh
+path.join(__dirname, 'node_modules/nhsuk-frontend/packages/components'),
+```
+
+Add
+
+```sh
+path.join(__dirname, 'node_modules/nhsapp-frontend/dist'),
+```
+
+So it looks like this
+
+```sh
+const appViews = [
+  path.join(__dirname, 'app/views/'),
+  path.join(__dirname, 'node_modules/nhsuk-frontend/packages/components'),
+  path.join(__dirname, 'node_modules/nhsapp-frontend/dist'),
+  path.join(__dirname, 'docs/views/'),
+];
+```
+
+## Step 5
+
+In your root folder, open
+
+```sh
+/app.js
+```
+
+and find
+
+```sh
+app.use('/nhsuk-frontend', express.static(path.join(__dirname, 'node_modules/nhsuk-frontend/dist')));
+```
+
+and on the next line paste
+
+```sh
+app.use('/nhsapp-frontend', express.static(path.join(__dirname, 'node_modules/nhsapp-frontend/dist/nhsapp')));
+```
+
 Once you have installed NHS App frontend, all NHS App components should work in your prototype.
 
 You will now have the latest version installed, later you can easily update to the latest NHS App frontend