ICU-20088 turn off liquid processing in MessageFormat page

docs/userguide/format_parse/messages/index.md

@@ -3,6 +3,8 @@
 License & terms of use: http://www.unicode.org/copyright.html
 -->
 
+{% raw  %}
+
 # Formatting Messages
 
 ## Overview
@@ -215,3 +217,5 @@ was a disturbance in the Force on planet 7."
 
 There are several more usage examples for the MessageFormat and ChoiceFormat
 classes in [C , C++ and Java](examples.md).
+
+{% endraw %}