Create guide with Composite pattern

Guides/code-pattern.md

@@ -0,0 +1,7 @@
+# Code patterns
+
+## Composite
+
+[Example from Autofac doc](https://autofaccn.readthedocs.io/en/latest/advanced/composites.html)
+
+Composite pattern with dependency injection can be very useful to migrate from a Legacy service to a new service smoothly.