Add custom stylesheet

-The custom.scss file can be used to add custom css changes without affecting the ability to do a git pull update
-Added a quick explanation of using the custom.scss file in the "Configure Explorer Settings" section of the README

README.md

@@ -279,6 +279,8 @@ cp ./settings.json.template ./settings.json
 
 *Make required changes in settings.json*
 
+**NOTE:** You can further customize the site by adding css rules to the `public/css/custom.scss` file. Adding changes to `custom.scss` is the preferred method of customizing the css rules for your site, without affecting the ability to receive explorer code updates in the future.
+
 ### Start/Stop the Explorer
 
 #### Start Explorer (Use for Testing)

public/css/custom.scss

@@ -0,0 +1 @@
+/* Add custom css rules here */