Several months ago, hassio was renamed to Home Assistant OS.
If you don’t see the Supervisor icon in the main menu (which leads to Add-Ons) it appears you have installed what is known as Home Assistant Container. What you have is the docker version of Home Assistant Core without any of the management conveniences provided by Supervisor (which is included in Home Assistant OS and Home Assistant Supervised).
The table in this post should help to clarify the four ways you can install Home Assistant and their relative differences: