docs: improve installation writuep

Author: chriskrycho

docs/installation.md

@@ -6,7 +6,9 @@ You can simply `ember install` the dependency like normal:
 ember install ember-cli-typescript@latest
 ```
 
-All dependencies will be added to your `package.json`, and you're ready to roll! **If you're upgrading from a previous release, see below!** you should check to merge any tweaks you've made to `tsconfig.json`.
+All dependencies will be added to your `package.json`, and you're ready to roll!
+
+**If you're upgrading from a previous release, see (./upgrade-notes.md).**
 
 Installing ember-cli-typescript modifies your project in two ways:
 
@@ -21,14 +23,14 @@ We install all of the following packages at their current "latest" value, :
 * `ember-cli-typescript-blueprints`
 * `@types/ember`
 * `@types/ember-data`
-* `@types/ember__*`
-* `@types/ember-data__*`
+* `@types/ember__*` – `@types/ember__object` for `@ember/object` etc.
+* `@types/ember-data__*` – `@types/ember-data__model` for `@ember-data/model` etc.
 * `@types/rsvp`
 * `@types/ember__test-helpers`
 
 ## Files this addon generates
 
-We add the following files to your project:
+We also add the following files to your project:
 
 * [`tsconfig.json`](https://www.typescriptlang.org/docs/handbook/tsconfig-json.html)
 * `types/<app name>/index.d.ts` – the location for any global type declarations you need to write for you own application; see [**Using TS Effectively: Global types for your package**](https://github.com/typed-ember/ember-cli-typescript/tree/3a434def8b8c8214853cea0762940ccedb2256e8/docs/getting-started/docs/ts/using-ts-effectively/README.md#global-types-for-your-package) for information on its default contents and how to use it effectively