UX: Update copy indicating page is machine-translated (#219)

Update copy for experimental topic translation "Show Original" button.

Author: nattsw

config/locales/client.en.yml

@@ -8,7 +8,7 @@ en:
     translator:
       view_translation: "View translation"
       hide_translation: "Hide translation"
-      content_not_translated: "Content not translated. Click to translate"
-      content_translated: "Content is translated. Click to view original"
+      content_not_translated: "Page not translated. Click to translate"
+      content_translated: "Page is machine-translated. Click to view original"
       translated_from: "Translated from %{language} by %{translator}"
       translating: "Translating"