Update theme info

flaskbb/themes/aurora/info.json

@@ -4,6 +4,8 @@
     "name": "Aurora",
     "author": "sh4nks",
     "license": "BSD 3-Clause",
+    "website": "https://flaskbb.org",
     "description": "The default theme for FlaskBB.",
+    "preview": "preview.png",
     "version": "1.0.0"
 }