Tweak heading formatting

docs/arch/adr-001.md

@@ -4,7 +4,7 @@ ADR 1: Component architecture for sidebar application
 Context
 -------
 
-## Background
+### Background
 
 Historically front-end web frameworks, including Angular 1.x, used a variety of
 MVC-based patterns for structuring the user interface part of an application
@@ -36,7 +36,7 @@ controllerAs). Angular JS 1.5x introduced [explicit
 support](https://docs.angularjs.org/guide/component) for this architecture via
 `.component()`.
 
-## Components in the client
+### Components in the client
 
 The client historically used traditional Angular 1.x methods of passing data
 between parts of the UI - properties on the scope inherited by child scopes and