Describe stability flags more consistently

doc/04-schema.md

@@ -263,7 +263,7 @@ All links are optional fields.
 These allow you to further restrict or expand the stability of a package beyond
 the scope of the [minimum-stability](#minimum-stability) setting. You can apply
 them to a constraint, or just apply them to an empty constraint if you want to
-allow unstable packages of a dependency's dependency for example.
+allow unstable packages of a dependency for example.
 
 Example:
 
@@ -274,6 +274,18 @@ Example:
         }
     }
 
+If one of your dependencies has a dependency on an unstable package you need to
+explicitly require it as well, along with its sufficient stability flag.
+
+Example:
+
+    {
+        "require": {
+            "doctrine/doctrine-fixtures-bundle": "dev-master",
+            "doctrine/data-fixtures": "@dev"
+        }
+    }
+
 `require` and `require-dev` additionally support explicit references (i.e.
 commit) for dev versions to make sure they are locked to a given state, even
 when you run update. These only work if you explicitly require a dev version