Fix image size for marketplace in Readme.

README.md

@@ -132,7 +132,7 @@ The app instance could be customized by passing following variables to NodeJS en
 | id | `string` | Used as slug for the app. Must be unique in the app list. | `'app'` |
 | external | `boolean` | If true means that the application opens in a new window, but not in an iframe. | `true` |
 | title | `string` | Displayed title of the app. | `'The App'` |
-| logo | `string` | URL to logo file. Should be at least 144x144. | `'https://foo.app/icon.png'` |
+| logo | `string` | URL to logo file. Should be at least 288x288. | `'https://foo.app/icon.png'` |
 | shortDescription | `string` | Displayed only in the app list. | `'Awesome app'` |
 | categories | `Array<MarketplaceCategoryId>` | Displayed category. Select one of the following bellow. | `['security', 'tools']` |
 | author | `string` | Displayed author of the app | `'Bob'` |