I’ll arbitrarily differentiate between topics and categories by saying that topics are like super-categories. They have their own pages (linked to under How-To Guides in the navigation bar) and may contain multiple categories. None of this is official Jekyll terminology, I just made it up to make explaining this easier.
Creating a New Topic
Jekyll uses liquid to process the HTML templates that make up the website. I’ve set it up to categorize any post that uses the landing layout as a topic page. For the sensor integration topic, here is the entirety of the file that makes up the topic page:
---
layout: landing
title: Sensor Integration Guides
author: Courtney McBeth
categories: ['Communication Protocols', 'Sensors']
logo: adafruit_logo.png
permalink: /sensors/
---
To create your own new topic, follow that format. List any categories under that topic in the categories array and set the permalink to something concise and informative. After you push this new file to GitHub, you should see a new topic in the drop down menu.
Creating a New Category
If you’d like to create a new category within an existing topic, all you have to do is add the new category name within the categories array of the topic file of your choosing.