add upgrade instructions

Release 1.1.0 introduced a BC break in the `CloudInterface`. This
commit adds a warning and additional upgrade instructions for users
implementing this interface.

CHANGELOG.md

@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+1.1.1
+-----
+
+* update installation instructions regarding the BC break introduced in 1.1.0
+
 1.1.0
 -----
 

README.md

@@ -9,6 +9,10 @@ PandaClient
 The PandaClient package provides an easy to use implementation of the
 [Panda encoding services](https://www.pandastream.com/) REST API.
 
+**Caution:** Version 1.1.0 introduced a BC break for users implementing the
+`CloudInterface`. Read the [upgrade instructions](UPGRADE-1.1.md) for more
+information.
+
 Installation
 ------------
 

UPGRADE-1.1.md

@@ -0,0 +1,41 @@
+Upgrade from 1.0 to 1.1
+=======================
+
+The `encodeVideoByUrl()` and `encodeVideoFile()` method got additional parameters.
+If you implement this interface, you'll have to reflect these changes.
+
+Before:
+
+```php
+// ...
+
+public function encodeVideoByUrl($url)
+{
+    // ...
+}
+
+public function encodeVideoFile($localPath)
+{
+    // ...
+}
+
+// ...
+```
+
+After:
+
+```php
+// ...
+
+public function encodeVideoByUrl($url, array $profiles = array(), $pathFormat = null, $payload = null)
+{
+    // ...
+}
+
+public function encodeVideoFile($localPath, array $profiles = array(), $pathFormat = null, $payload = null)
+{
+    // ...
+}
+
+// ...
+```