Added documentation for #139 in migration doc

Author: weierophinney

Diff for: doc/book/migration/to-v3-0.md

@@ -410,6 +410,35 @@ $ composer require zendframework/zend-validator
 Note: the above assumes you have already installed zend-component-installer, per
 the section above on [dependency reduction](#dependency-reduction).
 
+## Zend\Mvc\View\InjectTemplateListener
+
+The `InjectTemplateListener` attempts to map a controller *service* name to a
+template using a variety of heuristics, including an explicit map provided
+during configuration, or auto-detection based on the service name. 
+
+In version 2, the autodetection took into consideration the `__NAMESPACE__`
+provided in routing configuration, and would omit the module subnamespace if a
+match was found. This caused issues when multiple modules shared a top-level
+namespace (e.g., `ZF\Apigility` and `ZF\Apigility\Admin`) if each had a
+controller with the same name.
+
+To avoid naming conflicts, version 3 removes this aspect of autodetection, and
+instead provides exactly one workflow for mapping:
+
+- Strip the `Controller` subnamespace, if present (e.g.,
+  the namespace `Application\Controller\\` is normalized to
+  `Application\\`).
+- Strip the `Controller` suffix in the class name, if present (e.g.,
+  `IndexController` is normalized to `Index`).
+- Inflect CamelCasing to dash-separated (e.g., `ShowUsers` becomes
+  `show-users`).
+- Replace the namespace separator with a slash.
+
+As a full example, the controller service name
+`TestSomething\With\Controller\CamelCaseController` will always map to
+`test-something/with/camel-case`, regardless of the `__NAMESPACE__` value
+provided in routing configuration.
+
 ## Zend\Mvc\View\SendResponseListener
 
 `Zend\Mvc\View\SendResponseListener` was deprecated with the 2.2 release, and