docs: fix broken header in callout block on Getting Started page (#4044)

Summary:
Changes the callout block header to separate the icon from the header of the callout.

The "information" callout at https://fbflipper.com/docs/getting-started/ displays the info icon and "RMATION".

![image](https://user-images.githubusercontent.com/11802078/187704594-2d9553b1-b754-48b9-b55d-7d64b2fd20ee.png)

## Changelog

Fixed broken header in a callout block in the getting started docs page

Pull Request resolved: #4044

Test Plan:
Build the docs and open `/docs/getting-started/`

**Static Docs Preview: flipper**
|[Full Site](https://our.intern.facebook.com/intern/staticdocs/eph/D39314921/V4/flipper/)|

|**Modified Pages**|
|[docs/getting-started](https://our.intern.facebook.com/intern/staticdocs/eph/D39314921/V4/flipper/docs/getting-started/)|

Reviewed By: lawrencelomax

Differential Revision: D39314921

Pulled By: lblasa

fbshipit-source-id: 0d7edc28e5457e0f68e93e871b3518711d35ccc1

docs/getting-started/index.mdx

@@ -41,7 +41,7 @@ To work properly with mobile apps, Flipper requires the following:
 
 If you are hacking a JS app, you should be good to go without any extra dependencies installed.
 
-:::information
+:::info Information
 [Experimental] Alternatively, it is possible to run a browser based version of Flipper directly from NPM by using `npx flipper-server`.
 :::