Release the Commands API and add docs for Apps.

chrome/common/extensions/api/_manifest_features.json

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // See c/c/e/features/* to understand this file, in particular feature.h,
 // simple_feature.h, and base_feature_provider.h.
 
 {
   "app": {
     "channel": "stable",
@@ skipping 93 matching lines @@
     "whitelist": [
       "CB2E4E7174A398FCB3AFA6840500C2E1D22DA7B2", // Bookmark Manager
       "D5736E4B5CF695CB93A2FB57E4FDC6E5AFAB6FE2", // http://crbug.com/312900
       "D57DE394F36DC1C3220E7604C575D29C51A6C495"  // http://crbug.com/319444
     ]
   }],
   "chrome_url_overrides": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"]
   },
-  "commands": [
-    {
-      "channel": "dev",
-      "extension_types": ["platform_app"],
-      "min_manifest_version": 2
-    }, {
-      "channel": "stable",
-      "extension_types": ["extension"],
-      "min_manifest_version": 2
-    }
-  ],
-  "commands.global": [
-    {
-      "channel": "dev",
-      "extension_types": ["extension", "platform_app"],
-      "min_manifest_version": 2
-    }
-  ],
+  "commands": {
+    "channel": "stable",
+    "extension_types": ["extension", "platform_app"],
+    "min_manifest_version": 2
+  },
   "content_pack": {
     "channel": "dev",
     "extension_types": ["extension"]
   },
   "content_security_policy": {
     "channel": "stable",
     // Platform apps have a restricted content security policy that cannot be
     // overriden (except for a whitelist of exceptions, see the
     // app.content_security_policy whitelist).
     "extension_types": ["extension", "legacy_packaged_app"]
@@ skipping 312 matching lines @@
       "extension_types": ["platform_app"],
       "location": "component"
     }
   ],
   "webview": {
     "channel": "stable",
     "extension_types": ["platform_app"],
     "min_manifest_version": 2
   }
 }