Add "kiosk_only" manifest attribute for platform apps.

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 57 matching lines @@
   },
   "incognito": {
     "documentation": "manifest/incognito.html",
     "example": "spanning or split"
   },
   "key": {
     "documentation": "manifest/key.html",
     "example": "publicKey"
   },
   "kiosk_enabled": {
-    "documentation": "manifest/kiosk_enabled.html",
+    "documentation": "manifest/kiosk_enabled.html#kiosk_enabled",
+    "example": true
+  },
+  "kiosk_only": {
+    "documentation": "manifest/kiosk_enabled.html#kiosk_only",
     "example": true
   },
   "manifest_version": {
     "documentation": "manifest/manifest_version.html",
     "example": 2,
     "level": "required"
   },
   "minimum_chrome_version": {
     "documentation": "manifest/minimum_chrome_version.html",
     "example": "versionString"
@@ skipping 62 matching lines @@
   "version": {
     "documentation": "manifest/version.html",
     "example": "versionString",
     "level": "required"
   },
   "web_accessible_resources": {
     "documentation": "manifest/web_accessible_resources.html",
     "example": []
   }
 }