Merge pull request #397 from DevOpsCraftsman/master

Propose Update to Manifesto: add parallel change / expand and contract

content/MinimumCD/CI/_index.md

@@ -22,6 +22,7 @@ Evolutionary coding methods:
 - [Keystone Interfaces](https://martinfowler.com/bliki/KeystoneInterface.html) (A.K.A [Dark Launching](https://martinfowler.com/bliki/DarkLaunching.html)) lets you deploy some portion of the code to production without being visible or usable by end-users. It can also let you review metrics on how well the feature behaves performance-wise before making it accessible.
 - [Branch by abstraction](https://www.branchbyabstraction.com/) is a good process for replacing existing new behaviors or frameworks with something new while constantly delivering. Also, a good pattern to use for A/B testing.
 - [Feature flags](https://martinfowler.com/articles/feature-toggles.html) can be temporary tools for feature release management or permanent tools for enabling behaviors for different personas. They can also be controlled with application configuration or dynamically with logic.
+- [Parallel Change](https://martinfowler.com/bliki/ParallelChange.html) (A.K.A. *Expand and Contract*) helps evolve APIs, database schemas, or internal contracts incrementally without breaking existing consumers. It involves introducing a new version alongside the old one (*expand*), gradually migrating usage, and finally removing the deprecated version (*contract*).
 
 ## What is Improved