[Docs] Various fixes (#2136)

* [Docs] Various fixes

* More fixes

* Fix ADRs

* Typo

docs/overview/background.md

@@ -0,0 +1,30 @@
+---
+id: background
+title: The Spotify Story
+---
+
+Backstage was born out of necessity at Spotify. We found that as we grew, our
+infrastructure was becoming more fragmented, our engineers less productive.
+
+Instead of building and testing code, teams were spending more time looking for
+the right information just to get started. “Where’s the API for that service
+we’re all supposed to be using?” “What version of that framework is everyone
+on?” “This service isn’t responding, who owns it?” “I can’t find documentation
+for anything!”
+
+Context switching and cognitive overload were dragging engineers down, day by
+day. We needed to make it easier for our engineers to do their work without
+having to become an expert in every aspect of infrastructure tooling.
+
+Our idea was to centralize and simplify end-to-end software development with an
+abstraction layer that sits on top of all of our infrastructure and developer
+tooling. That’s Backstage.
+
+It’s a developer portal powered by a centralized service catalog — with a plugin
+architecture that makes it endlessly extensible and customizable.
+
+Manage all your services, software, tooling, and testing in Backstage. Start
+building a new microservice using an automated template in Backstage. Create,
+maintain, and find the documentation for all that software in Backstage.
+
+One place for everything. Accessible to everyone.