(docs): add Related Libraries section

- kind of self-promotion, though they were built together for a
  similar purpose of building an ad-hoc API with Django
  - but they could be used separately and for other reasons

Author: agilgur5

README.md

@@ -10,7 +10,8 @@ Django classes to make your models, managers, and querysets serializable, with b
 I. [Installation](#installation) <br />
 II. [Usage](#usage) <br />
 III. [How it Works](#how-it-works) <br />
-IV. [Backstory](#backstory)
+IV. [Related Libraries](#related-libraries) <br />
+V. [Backstory](#backstory)
 
 
 ## Installation
@@ -217,6 +218,14 @@ In order to recurse over relations / joins, it accepts the same arguments as the
 I'd encourage you to read the source code, since it's shorter than this README :)
 
 
+## Related Libraries
+
+1. [django-api-decorators](https://github.com/agilgur5/django-api-decorators)
+  - `Tiny decorator functions to make it easier to build an API using Django in ~100 LoC`
+
+
+<br>
+
 ## Backstory
 
 This library was built while I was working on [Yorango](https://github.com/Yorango)'s ad-hoc API. Writing code to serialize various models was complex and quite tedious, resulting in messy spaghetti code for many of our API methods. The only solutions I could find online were the [Django Full Serializers](http://code.google.com/p/wadofstuff/wiki/DjangoFullSerializers) from [wadofstuff](https://github.com/mattimustang/wadofstuff) as well as some recursive `model_to_dict` snippets online -- none of which gave the option for customizable whitelists and blacklists on a per Model basis.