Fix styling for custom layout docs
Fix styling for custom layout docs

Summary:
We can't use monospace in headlines without messing up the styling.

This is what it looked like before:
{F66859104}

Fix #170

Reviewed By: mihaelao

Differential Revision: D5002205

fbshipit-source-id: cedf36c71ba76ccf703b81851ecad1442dce3f77

facebook/litho,facebook/litho,facebook/litho,facebook/litho,facebook/litho,facebook/litho