Enable release notes translation

Releasenote translation publishing is being prepared. 'locale_dirs'
needs to be defined in conf.py to generate translated version of the
release notes.

Change-Id: Ibf005a434417c7b6ad7b7bada27d45f3bf238db1

releasenotes/source/conf.py

@@ -257,3 +257,6 @@ texinfo_documents = [
 
 # If true, do not generate a @detailmenu in the "Top" node's menu.
 #texinfo_no_detailmenu = False
+
+# -- Options for Internationalization output ------------------------------
+locale_dirs = ['locale/']