Merge pull request #33 from JackPrice/JackPrice-patch-1

Capitalise SHOULD

Author: moufmouf

docs/ContainerInterface.md

@@ -40,7 +40,7 @@ Users of dependency injections containers (DIC) are refered to as `user`.
 Exceptions directly thrown by the container MUST implement the 
 [`Interop\Container\Exception\ContainerException`](../src/Interop/Container/Exception/ContainerException.php).
 
-A call to the `get` method with a non-existing id should throw a
+A call to the `get` method with a non-existing id SHOULD throw a
 [`Interop\Container\Exception\NotFoundException`](../src/Interop/Container/Exception/NotFoundException.php).
 
 ### 1.3 Additional features