Philosophy: maintenance (#261)

Author: andyblundell

README.md

@@ -19,6 +19,7 @@ It aims to:
 The philosophy underpinning this framework advocates:
 * Engineering led by user needs and service outcomes
 * Empowered delivery teams which are accountable for their products
+* Products must be actively maintained for their entire lifecycle
 * Rapid, iterative and incremental development: "Release early. Release often. And listen to your customers." (Eric S. Raymond in [The Cathedral and the Bazaar](https://en.wikipedia.org/wiki/The_Cathedral_and_the_Bazaar))
 * Robust and comprehensive automation supporting and enforcing quality 
 * Reliable & scalable services, remembering "Everything fails, all the time" (Werner Vogels), and treating operations as a software engineering challenge (as in Google's [Site Reliability Engineering](https://landing.google.com/sre/))