Folder + readme for Chapter 4 : Factory

Author: dancergraham

README.md

@@ -1,6 +1,6 @@
 # HeadFirstDesignPatterns_python
 
-<img src="images\learning.oreilly.jpg" alt="Girl in a jacket" width="200" align="right">Example code from [Head First Design Patterns second edition](https://www.wickedlysmart.com/head-first-design-patterns/) translated to python to help me understand and memorise the patterns.  
+<img src="images\learning.oreilly.jpg" alt="Head First Design Patterns Second Edition" width="200" align="right">Example code from [Head First Design Patterns second edition](https://www.wickedlysmart.com/head-first-design-patterns/) translated to python to help me understand and memorise the patterns.  
 
 I am aiming for a literal translation without trying to make the code pythonic beyond, e.g. using python conventions for `ClassNames` and `method_names` and putting all of the code in a single file where it makes sense to do so.
 

chapter04_factory/readme.md

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+# Chapter 4: Factory patterns
+
+**Simple Factory**: A class which chooses which product class to instantiate and return, based upon method parameters.
+
+**Factory Method**: Define an interface for creating an object, but let subclasses decide which class to instantiate. The Factory method lets a class defer instantiation it uses to subclasses.
+
+**Abstract Factory**: Provide an interface for creating families of related or dependent objects without specifying their concrete classes.