add news bullet

Author: lorenzwalthert

NEWS.md

@@ -33,6 +33,9 @@
 
 * Escape characters in roxygen code examples are now correctly escaped (#512).
 
+* Special characters such as `\n` in strings are now preseved in text and not 
+  turned into literal values like a line break (#554).
+
 * Style selection Addin now preserves line break when the last line selected is
   an entire line (#520).