Write docs for options_ui

chrome/common/extensions/docs/templates/json/manifest.json

 {
   "app": {
     "documentation": "manifest/app.html",
     "example": {},
     "level": "required"
   },
   "app.background": {
     "example": {"scripts": ["background.js"]},
     "level": "required"
   },
@@ skipping 113 matching lines @@
     "example": true
   },
   "omnibox": {
     "documentation": "omnibox.html",
     "example": {
       "keyword": "aString"
     }
   },
   "options_page": {
     "documentation": "options.html",
-    "example": "aFile.html"
+    "example": "options.html"
+  },
+  "options_ui": {
+    "documentation": "optionsV2.html",
+    "example": {
+      "page": "options.html",
+      "chrome_style": true
+    }
   },
   "page_action": {
     "documentation": "pageAction.html",
     "example": {},
     "level": "only_one"
   },
   "permissions": {
     "documentation": "declare_permissions.html",
     "example": []
   },
@@ skipping 45 matching lines @@
   },
   "web_accessible_resources": {
     "documentation": "manifest/web_accessible_resources.html",
     "example": []
   },
   "webview": {
     "documentation": "tags/web_view#local_resources",
     "example": {}
   }
 }