Added the full namespace to interfaces

Author: ezimuel

docs/book/auth-adapter.md

@@ -1,7 +1,8 @@
 # Authentication adapters
 
 The authentication adapters for `zend-expressive-authentication` implement the
-interface `AuthenticationInterface` reported below:
+interface `Zend\Expressive\Authentication\AuthenticationInterface` reported
+below:
 
 ```php
 namespace Zend\Expressive\Authentication;

docs/book/intro.md

@@ -11,7 +11,7 @@ delegate in the pipeline, passing a [UserInterface](https://github.com/zendframe
 object as attribute in the request. If the request is not authenticated, the
 middleware returns a `401 Unauthorized` response.
 
-The `UserInterface` is defined as follows:
+The `Zend\Expressive\Authentication\UserInterface` is defined as follows:
 
 ```php
 namespace Zend\Expressive\Authentication;

docs/book/user-repository.md

@@ -3,9 +3,8 @@
 An authentication adapter can take the information about the users from
 different repository: a [htpasswd](https://httpd.apache.org/docs/current/programs/htpasswd.html)
 file, a database, a custom repository, etc. We provided an interface, the
-`UserRepositoryInterface`, to access the user storage.
-
-The `UserRepositoryInterface` is reported below:
+`Zend\Expressive\Authentication\UserRepositoryInterface`, to access the user
+storage. This interface is reported below:
 
 ```php
 namespace Zend\Expressive\Authentication;