add denote all optional arguments in readme

README.md

@@ -32,24 +32,23 @@ module.exports = React.createClass({
 
 ## Documentation
 
-#### `r[tag]([properties], children)`
+#### `r[tag]([properties], [children])`
 
 Returns a React element
 
 - **tag** `String` - A React.DOM tag string
-- **properties** `Object` - An object containing the properties you'd like to set on the element. Defaults to `{}`.
-- **children** `Array|String` - An array of `r` children or a string. This will create child elements or a text node, respectively.
+- **properties** `Object` *optional* - An object containing the properties you'd like to set on the element.
+- **children** `Array|String` *optional* - An array of `r` children or a string. This will create child elements or a text node, respectively. 
 
-#### `r(component, [properties], children)`
+#### `r(component, [properties], [children])`
 
 Returns a React element
 
 - **component** `Function` - A React.js Component class created with `React.createClass`
-- **properties** `Object` - An object containing the properties you'd like to set on the element.  Defaults to `{}`.
-- **children** `Array|String` - An array of `r` children or a string. This will create child elements or a text node, respectively.
+- **properties** `Object` *optional* - An object containing the properties you'd like to set on the element.
+- **children** `Array|String` *optional* - An array of `r` children or a string. This will create child elements or a text node, respectively. 
 
 #### Special Properties
 
-- **isRendered** `"Boolean"` - If falsy, React will skip rendering the target component.
-
-- **classSet** `Object` - Apply [classnames](https://www.npmjs.com/package/classnames) and assign to className.
+- **isRendered** `"Boolean"` *optional* - If falsy, React will skip rendering the target component.
+- **classSet** `Object` *optional* - Apply [classnames](https://www.npmjs.com/package/classnames) and assign to className.