Add upgrade docs

docs/upgrades/upgrade_100_200.rst

@@ -1,2 +1,16 @@
 Upgrading from 1.0.0 to 2.0.0
 =============================
+
+eZ Platform Site API introduces a slight breaking change to ``ContentView`` value object, hence the
+bump to version 2.0.
+
+- Site API ``ContentView`` view object does not extend from eZ Platform ``ContentView`` value object
+  any more to allow implementation of custom view providers. Class signature did not change,
+  however, since all required interfaces are now implemented directly on Site API ``ContentView``
+  value object.
+
+- Also, ``Netgen\Bundle\EzPlatformSiteApiBundle\View\ContentValueView`` interface does not contain
+  ``getSiteLocation`` method any more. It is moved to a new interface, ``LocationValueView``, in the
+  same namespace. If you used this method in your code, make sure to check for this new interface.
+  This was done to keep in line on how eZ kernel uses its ``ContentView`` value object and its
+  interfaces.

docs/upgrades/upgrade_230_240.rst

@@ -1,2 +1,22 @@
 Upgrading from 2.3.0 to 2.4.0
 =============================
+
+Controllers that extend from ``Netgen\Bundle\EzPlatformSiteApiBundle\Controller\Controller`` and are
+registered inside dependency injection container should set two setter injection ``calls``:
+
+.. code-block:: yaml
+
+    app.demo.controller.demo_controller:
+        class: Acme\Bundle\DemoBundle\Controller\DemoController
+        calls:
+            - [setContainer, ['@service_container']]
+            - [setSite, ['@netgen.ezplatform_site.site']]
+
+
+Or if you want to avoid setter calls, just set ``parent`` service:
+
+.. code-block:: yaml
+
+    app.demo.controller.demo_controller:
+        parent: netgen.ezplatform_site.controller.base
+        class: Acme\Bundle\DemoBundle\Controller\DemoController