The actual article title should be formatted as "Topic Overview". I.e. Flow Overview. Repeat the title for the first header name in the article using the H2 button, as shown below.
Overview
Once a Formula is created there are a few different ways that it can be added into builds. This document goes over the methods of utilizing Formulas
In Flows
If the overview needs a sub-section to explain something with a bit more depth or importance, the H3 button can be used to title the sub-section.