minor typo fixes in README files

Author: Elise Kain

README.md

@@ -101,7 +101,7 @@ ReactDOM.render(
 
 [demo](http://ruanyf.github.io/react-demos/demo03/) / [source](https://github.com/ruanyf/react-demos/blob/master/demo03/index.html)
 
-If a JavaScript variable is array, JSX will implicitly concat all members of the array.
+If a JavaScript variable is an array, JSX will implicitly concat all members of the array.
 
 ```js
 var arr = [
@@ -135,7 +135,7 @@ ReactDOM.render(
 
 Components would have attributes, and you can use `this.props.[attribute]` to access them, just like `this.props.name` of `<HelloMessage name="John" />` is John.
 
-Please remember the first letter of the component's name must be capitalized, otherwise React will throw an error. For instance, `HelloMessage` as a component's name is OK, but `helloMessage` is not allowed. And a React component should only one top child node.
+Please remember the first letter of the component's name must be capitalized, otherwise React will throw an error. For instance, `HelloMessage` as a component's name is OK, but `helloMessage` is not allowed. And a React component should only have one top child node.
 
 ```javascript
 // wrong
@@ -190,7 +190,7 @@ ReactDOM.render(
 );
 ```
 
-Please be minded that the value of `this.props.children` has three possibilities. If the component has no children node, the value is `undefined`; If single children node, an object; If multiple children nodes, an array. You should be careful to handle it.
+Please be mindful that the value of `this.props.children` has three possibilities. If the component has no children node, the value is `undefined`; If single children node, an object; If multiple children nodes, an array. You should be careful to handle it.
 
 React gave us an utility [`React.Children`](https://facebook.github.io/react/docs/top-level-api.html#react.children) for dealing with the `this.props.children`'s opaque data structure. You could use `React.Children.map` to iterate `this.props.children` without worring its data type being `undefined` or `object`. Check [official document](https://facebook.github.io/react/docs/top-level-api.html#react.children) for more methods `React.Children` offers.
 
@@ -216,7 +216,7 @@ var MyTitle = React.createClass({
 });
 ```
 
-The above component of `Mytitle` has a props of `title`. PropTypes tells React that the title is required and its value should be string.
+The above component of `MyTitle` has a props of `title`. PropTypes tells React that the title is required and its value should be a string.
 
 Now we give `Title` a number value.
 
@@ -229,7 +229,7 @@ ReactDOM.render(
 );
 ```
 
-It means the props doesn't pass the validation, and the console will show you a error message.
+It means the props doesn't pass the validation, and the console will show you an error message.
 
 ```bash
 Warning: Failed propType: Invalid prop `title` of type `number` supplied to `MyTitle`, expected `string`.
@@ -285,7 +285,7 @@ ReactDOM.render(
 );
 ```
 
-The desired DOM node should have a `ref` attribute, and `this.refs.[refName]` would return the corresponding DOM node. Please be minded that you could do that only after this component has been mounted into the DOM, otherwise you get `null`.
+The desired DOM node should have a `ref` attribute, and `this.refs.[refName]` would return the corresponding DOM node. Please be mindful that you could do that only after this component has been mounted into the DOM, otherwise you get `null`.
 
 ## Demo08: this.state
 

demo13/README.md

@@ -1,7 +1,7 @@
 This demo is copied from [github.com/mhart/react-server-example](https://github.com/mhart/react-server-example), but I rewrote it with JSX syntax.
 
 ```bash
-# install the dependencies in demo12 directory
+# install the dependencies in demo13 directory
 $ npm install
 
 # translate all jsx file in src subdirectory to js file