Emphasis on single child.

docs/api.md

@@ -50,7 +50,7 @@ React.createClass({
 function createClass(object specification)
 ```
 
-Creates a component given a specification. A component implements a `render` method which returns a single child. That child may have an arbitrarily deep child structure. One thing that makes components different than a standard prototypal classes is that you don't need to call new on them. They are convenience wrappers that construct backing instances (via new) for you.
+Creates a component given a specification. A component implements a `render` method which returns **one single** child. That child may have an arbitrarily deep child structure. One thing that makes components different than a standard prototypal classes is that you don't need to call new on them. They are convenience wrappers that construct backing instances (via new) for you.
 
 #### React.renderComponent