add Trend reverseColor doc

src/components/Trend/demo/basic.md

@@ -10,7 +10,7 @@ import Trend from 'ant-design-pro/lib/Trend';
 
 ReactDOM.render(
   <div>
-    <Trend flag="up">12%</Trend>
+    <Trend flag="up" >12%</Trend>
     <Trend flag="down" style={{ marginLeft: 8 }}>11%</Trend>
   </div>
 , mountNode);

src/components/Trend/demo/reverse.md

+---
+order: 0
+title: 颜色反转
+---
+
+在数值背后添加一个小图标来标识涨跌情况。
+
+````jsx
+import Trend from 'ant-design-pro/lib/Trend';
+
+ReactDOM.render(
+  <div>
+    <Trend flag="up" reverseColor={true} >12%</Trend>
+    <Trend flag="down" reverseColor={true} style={{ marginLeft: 8 }}>11%</Trend>
+  </div>
+, mountNode);
+````

src/components/Trend/index.d.ts

@@ -4,6 +4,7 @@ export interface ITrendProps {
   colorful?: boolean;
   flag: 'up' | 'down';
   style?: React.CSSProperties;
+  reverseColor?: boolean;
 }
 
 export default class Trend extends React.Component<ITrendProps, any> {}

src/components/Trend/index.md

@@ -19,3 +19,4 @@ order: 14
 |----------|------------------------------------------|-------------|-------|
 | colorful | 是否彩色标记 | Boolean | true |
 | flag | 上升下降标识：`up|down` | string | - |
+| reverseColor | 颜色反转 | Boolean | true |