Correct capitalization of 'XliffAPI' (#6181)

* Correct capitalization of 'XliffAPI'

* Correct capitalization of 'API' in XLIFF documentation

* Fix capitalization of 'XliffAPI' to 'XliffApi'

Author: morange

Documentation/ApiOverview/Localization/XliffApi.rst

@@ -1,10 +1,10 @@
-:navigation-title: XLIFF Api
+:navigation-title: XLIFF API
 
 ..  include:: /Includes.rst.txt
 ..  _xliff-api:
 
 =================================
-XLIFF Api: Access language labels
+XLIFF API: Access language labels
 =================================
 
 ..  contents:: Table of contents