docs: about-us link shows Page Not Found for a fraction of a seco…

…nd (#3)

Apparently the website shows a Page Not Found for less than a
millisecond to then show the content, removing the last / from the URL
seems to be the "correct" url for that page.

README.md

@@ -4,7 +4,7 @@
 
 [Celest](https://celest.dev) is the Flutter cloud platform. We enable Flutter and Dart developers to declaratively define their backend infrastructure in Dart.
 
-You can join our waitlist at [celest.dev](https://celest.dev). To learn more about our values and how we operate, visit our [about us](https://celest.dev/about-us/) page.
+You can join our waitlist at [celest.dev](https://celest.dev). To learn more about our values and how we operate, visit our [about us](https://celest.dev/about-us) page.
 
 ## Connect with us