move 2.19 to deprecated and remove dev docs routes for 2.19 from static redirect file

Author: sarahs

lib/enterprise-server-releases.js

@@ -7,10 +7,10 @@ const dates = require('../lib/enterprise-dates.json')
 const supported = [
   '2.22',
   '2.21',
-  '2.20',
-  '2.19'
+  '2.20'
 ]
 const deprecated = [
+  '2.19',
   '2.18',
   '2.17',
   '2.16',