Add missing "tw" entry in flags.json for tw.svg (#2217)

Co-authored-by: Paweł Kuna <1282324+codecalm@users.noreply.github.com>
Co-authored-by: codecalm <codecalm@gmail.com>

.changeset/popular-geckos-flow.md

@@ -0,0 +1,5 @@
+---
+"preview": patch
+---
+
+Add missing `tw` entry in `flags.json`

preview/pages/_data/flags.json

@@ -915,6 +915,10 @@
     "name": "Tuvalu",
     "flag": "tv"
   },
+  {
+    "name": "Taiwan",
+    "flag": "tw"
+  },
   {
     "name": "Tanzania",
     "flag": "tz"
@@ -995,4 +999,4 @@
     "name": "Zimbabwe",
     "flag": "zw"
   }
-]
+]