📝 improve README.md

Signed-off-by: Vinicius Reis <vinicius.reis@nextcloud.com>

Author: Vinicius Reis

README.md

@@ -7,8 +7,12 @@ Simple, typed wrapper of an Axios instance for Nextcloud that automatically send
 
 ## Installation
 
+```sh
+npm install @nextcloud/axios --save
 ```
-npm i -S @nextcloud/axios
+
+```sh
+yarn add @nextcloud/axios
 ```
 
 ## Usage
@@ -20,3 +24,21 @@ axios.get('nextcloud.com')
 ```
 
 See https://github.com/axios/axios for details.
+
+### Defining `baseURL`
+
+You are able to define [`baseURL`](https://axios-http.com/docs/config_defaults) to simplify the usage of axios across your app.
+
+```ts
+import axios from '@nextcloud/axios'
+import { generateUrl } from '@nextcloud/router'
+
+const baseURL = generateUrl('/apps/your_app_id/api')
+
+axios.defaults.baseURL = baseURL
+```
+
+References
+
+- [@nextcloud/router](https://github.com/nextcloud/nextcloud-router)
+- [Nextcloud App Routing](https://docs.nextcloud.com/server/latest/developer_manual/basics/routing.html)