docs: duplicate content on the About page

**Link to the affected page or pages**
Location: https://fly.io/docs/about/
Source: https://github.com/superfly/docs/blob/main/about/index.html.markerb

**Describe what parts of the doc need improvement**
There is a duplicate [Open Source](https://fly.io/docs/about/open-source/) listing on the About page.

**Additional info**
