Add deprecation guide for ds.deprecated-initializers #2780

source/deprecations/ember-data/v2.x.html.md

@@ -676,3 +676,39 @@ Using `JSONAPISerializer.payloadKeyFromModelName` to serialize the type of a
 See [JSONAPISerializer.payloadKeyFromModelName for
 Resource](#toc_jsonapiserializer-payloadkeyfrommodelname-for-resource) for more
 information.
+
+#### Unused Initializers
+
+###### until: 3.0.0
+###### id: ds.deprecated-initializers
+
+The Ember Data initializers `data-adapter`, `injectStore`, `transforms`, and `store` are no longer used, so they are being removed.
+Applications that depend on these for the ordering of their own custom initializers can substitute `ember-data` instead, without any change in functionality.
+
+Before:
+
+```javascript
+export function initialize(application) {
+  // ... your code ...
+};
+
+export default {
+  name: 'websocketInit',
+  after: 'store',
+  initialize: initialize
+};
+```
+
+After:
+
+```javascript
+export function initialize(application) {
+  // ... your code ...
+};
+
+export default {
+  name: 'websocketInit',
+  after: 'ember-data',
+  initialize: initialize
+};
+```