PLT-126: Change 'Private Messages' to 'Direct Messages'

Signed-off-by: Chengwei Yang <yangchengwei@qiyi.com>

web/react/components/more_direct_channels.jsx

@@ -114,7 +114,7 @@ export default class MoreDirectChannels extends React.Component {
                                 <span aria-hidden='true'>&times;</span>
                                 <span className='sr-only'>Close</span>
                             </button>
-                            <h4 className='modal-title'>More Private Messages</h4>
+                            <h4 className='modal-title'>More Direct Messages</h4>
                         </div>
                         <div className='modal-body'>
                             <ul className='nav nav-pills nav-stacked'>