Add JavaScript / Node.js as a first class backend langauge at GDS

source/standards/programming-languages.html.md.erb

@@ -58,15 +58,13 @@ Our core languages for backend development are:
 - [Java](/manuals/programming-languages/java.html)
 - [Python](/manuals/programming-languages/python/python.html)
 - [Ruby](/manuals/programming-languages/ruby.html)
+- [JavaScript / Node.js](/manuals/programming-languages/nodejs/index.html)
 
 We’ve chosen these languages because they are successfully used by
 teams at the moment, and we are confident in how to host and operate
 applications written in them. You should carry out new
 development in one of these languages.
 
-We are also currently exploring the use of Node.js in the backend for
-serverless systems, particularly in the Digital Identity programme.
-
 ### Python
 
 You should write new Python projects in Python 3.