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".  ## Changelog Fixed broken header in a callout block in the getting started docs page Pull Request resolved: https://github.com/facebook/flipper/pull/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