Add Card to README

Author: koppen

README.md

@@ -217,9 +217,13 @@ renders
 - **Outline Button**: `Flowbite::Button::Outline`
 - **Pill Button**: `Flowbite::Button::Pill`
 
+#### Cards
+- **Card**: `Flowbite::Card` (default card with content and title)
+
 #### Navigation
 - **Link**: `Flowbite::Link` (default link styling)
 
+
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies.