[docs] Cut SDK 49 beta docs

docs/package.json

@@ -1,6 +1,7 @@
 {
   "name": "expo-docs",
   "version": "48.0.0",
+  "betaVersion": "49.0.0",
   "private": true,
   "type": "module",
   "scripts": {

docs/pages/versions/v49.0.0/config/app.mdx

@@ -0,0 +1,17 @@
+---
+title: app.json / app.config.js
+maxHeadingDepth: 5
+---
+
+{/* Hi! If you found an issue within the description of the manifest properties, please create a GitHub issue. */}
+
+import AppConfigSchemaPropertiesTable from '~/components/plugins/AppConfigSchemaPropertiesTable';
+import schema from '~/public/static/schemas/unversioned/app-config-schema.json';
+
+The following is a list of properties that are available for you under the `"expo"` key in **app.json** or **app.config.json**. These properties can be passed to the top level object of **app.config.js** or **app.config.ts**.
+
+For more general information on app configuration, such as the differences between the various app configuration files, see [Configuration with app.json/app.config.js](/workflow/configuration/).
+
+## Properties
+
+<AppConfigSchemaPropertiesTable schema={schema} />