[docs] add reference to the explanation of capitalizing components

content/docs/components-and-props.md

@@ -90,6 +90,8 @@ Let's recap what happens in this example:
 >Always start component names with a capital letter.
 >
 >React treats components starting with lowercase letters as DOM tags. For example, `<div />` represents an HTML div tag, but `<Welcome />` represents a component and requires `Welcome` to be in scope.
+>
+>You can read more about the reasoning behind this convention [here.](https://reactjs.org/docs/jsx-in-depth.html#user-defined-components-must-be-capitalized)
 
 ## Composing Components