docs(kitsu-core): add migration guide link to README

Author: wopian

packages/kitsu-core/README.md

@@ -26,7 +26,10 @@
 
 <p align=center>Core <a href=http://jsonapi.org>JSON:API</a> serialisation and deserialisation components</p>
 
-# 
+
+<p align=center><a href=https://github.com/wopian/kitsu/blob/master/packages/kitsu-core/MIGRATING.md>Migration guide</a> for v9 and previous major releases</p>
+
+#
 
 ## Features
 
@@ -228,7 +231,7 @@ Filters includes for the specific relationship
 #### Parameters
 
 -   `included` **[Object](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object)** The response included object
--   `opts` **[Object](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object)** 
+-   `opts` **[Object](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object)**
     -   `opts.id` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** The relationship ID
     -   `opts.type` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** The relationship type
 
@@ -313,7 +316,7 @@ Split model name from the model's resource URL
 #### Parameters
 
 -   `url` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** URL path for the model
--   `options` **[Object](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object)** 
+-   `options` **[Object](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object)**
     -   `options.resourceCase` **[Function](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function)** Convert libraryEntries to library-entries or library_entries (default no conversion). To use parameter, import kebab or snake from kitsu-core
     -   `options.pluralModel` **[Function](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function)** Pluralise models (default no pluralisation). To use parameter, import pluralize (or another pluralisation npm package)