Added the name attribute to XLIFF 2 documents

Author: javiereguiluz

components/translation/usage.rst

@@ -438,7 +438,7 @@ loaded/dumped when using this component inside a Symfony application:
     <xliff xmlns="urn:oasis:names:tc:xliff:document:2.0" version="2.0"
            srcLang="fr-FR" trgLang="en-US">
       <file id="messages.en_US">
-        <unit id="LCa0a2j">
+        <unit id="LCa0a2j" name="original-content">
           <notes>
             <note category="state">new</note>
             <note category="approved">true</note>