Add information RE: ember-try configuration.

text/0558-edition-detection.md

@@ -52,6 +52,13 @@ The value will be expected to be one of the valid edition names (currently
 `classic` and `octane`). Using the `package.json` for this allows us to ensure
 that the value is statically analyzable and easy to discover.
 
+For applications specifying `ember: { edition: 'octane' }` in `package.json` is
+enough, but for addons they would need to be able to customize the target
+edition per test run so that they can easily test against many different
+edition's. In order to support this, ember-try will be updated to allow
+specifying (and merging) the `ember` property in the `package.json` from their
+`config/ember-try.js` scenarios.
+
 ### Valid use of the edition value
 
 The edition flag should only be used by addons to determine what blueprint