chore(docs) Remove extra style tag curly braces (#10973)

Removed an extra quoted set of curly braces..

_posts/2016-03-07-react-v15-rc1.md

@@ -79,7 +79,7 @@ Each of these changes will continue to work as before with a new warning until t
 ### New helpful warnings
 
 - If you use a minified copy of the _development_ build, React DOM kindly encourages you to use the faster production build instead.
-- React DOM: When specifying a unit-less CSS value as a string, a future version will not add `px` automatically. This version now warns in this case (ex: writing `style={{'{{'}}width: '300'}}`. (Unitless *number* values like `width: 300` are unchanged.)
+- React DOM: When specifying a unit-less CSS value as a string, a future version will not add `px` automatically. This version now warns in this case (ex: writing `style={{width: '300'}}`. (Unitless *number* values like `width: 300` are unchanged.)
 - Synthetic Events will now warn when setting and accessing properties (which will not get cleared appropriately), as well as warn on access after an event has been returned to the pool.
 - Elements will now warn when attempting to read `ref` and `key` from the props.
 - React DOM now attempts to warn for mistyped event handlers on DOM elements (ex: `onclick` which should be `onClick`)

_posts/2016-04-07-react-v15.md

@@ -143,7 +143,7 @@ Each of these changes will continue to work as before with a new warning until t
 - If you use a minified copy of the _development_ build, React DOM kindly encourages you to use the faster production build instead.  
 <small>[@sophiebits](https://github.com/sophiebits) in [#5083](https://github.com/facebook/react/pull/5083)</small>
 
-- React DOM: When specifying a unit-less CSS value as a string, a future version will not add `px` automatically. This version now warns in this case (ex: writing `style={{'{{'}}width: '300'}}`. Unitless *number* values like `width: 300` are unchanged.  
+- React DOM: When specifying a unit-less CSS value as a string, a future version will not add `px` automatically. This version now warns in this case (ex: writing `style={{width: '300'}}`. Unitless *number* values like `width: 300` are unchanged.  
 <small>[@pluma](https://github.com/pluma) in [#5140](https://github.com/facebook/react/pull/5140)</small>
 
 - Synthetic Events will now warn when setting and accessing properties (which will not get cleared appropriately), as well as warn on access after an event has been returned to the pool.  

docs/context.md

@@ -36,7 +36,7 @@ Suppose you have a structure like:
 class Button extends React.Component {
   render() {
     return (
-      <button style={{'{{'}}background: this.props.color}}>
+      <button style={{background: this.props.color}}>
         {this.props.children}
       </button>
     );
@@ -72,7 +72,7 @@ import PropTypes from 'prop-types';
 class Button extends React.Component {
   render() {
     return (
-      <button style={{'{{'}}background: this.context.color}}>
+      <button style={{background: this.context.color}}>
         {this.props.children}
       </button>
     );
@@ -166,7 +166,7 @@ Stateless functional components are also able to reference `context` if `context
 import PropTypes from 'prop-types';
 
 const Button = ({children}, context) =>
-  <button style={{'{{'}}background: context.color}}>
+  <button style={{background: context.color}}>
     {children}
   </button>;
 

docs/reconciliation.md

@@ -58,9 +58,9 @@ By comparing these two elements, React knows to only modify the `className` on t
 When updating `style`, React also knows to update only the properties that changed. For example:
 
 ```xml
-<div style={{'{{'}}color: 'red', fontWeight: 'bold'}} />
+<div style={{color: 'red', fontWeight: 'bold'}} />
 
-<div style={{'{{'}}color: 'green', fontWeight: 'bold'}} />
+<div style={{color: 'green', fontWeight: 'bold'}} />
 ```
 
 When converting between these two elements, React knows to only modify the `color` style, not the `fontWeight`.