Fix typo and remove duplicate Open Source entry in About section overview (#2323)

* chore(about): remove duplicate Open Source entry

Removed duplicate Open Source section from the About page.

* Fix typo in Engineering Jobs and Hiring section

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Co-authored-by: Kristin Martin <kcmartin@users.noreply.github.com>

Author: nyedidikeke

about/index.html.markerb

@@ -24,9 +24,7 @@ More details about using and working with the Fly.io platform.
 
 * **[Healthcare](/docs/about/healthcare/):** Controls relevant to running healthcare apps on Fly.io.
 
-* **[Engineering Jobs and Hiring](/docs/about/extensions/):** Learm more about our hiring process.
-
-* **[Open Source](/docs/about/open-source/):** How we help those OSS projects that help us.
+* **[Engineering Jobs and Hiring](/docs/about/extensions/):** Learn more about our hiring process.
 
 * **[Open Source](/docs/about/open-source/):** How we help those OSS projects that help us.