Explain Launch styling (#1692)

Author: chdeskur

fern/products/docs/pages/component-library/default-components/callouts.mdx

@@ -51,10 +51,10 @@ To display very short pieces of information like status indicators and version n
 
 ### Launch callouts
 
-<Launch>This celebrates a product launch or other announcement</Launch>
+<Launch>This celebrates an announcement, styled using the primary accent of the docs site</Launch>
 
 ```jsx
-<Launch>This celebrates an announcement</Launch>
+<Launch>This celebrates an announcement, styled using the primary accent of the docs site</Launch>
 ```