Input: update doc (#2283)

examples/docs/en-US/input.md

@@ -305,7 +305,11 @@ Prepend or append an element, generally a label or a button.
     <el-button slot="append" icon="search"></el-button>
   </el-input>
 </div>
-
+<style>
+  .el-select .el-input {
+    width: 110px;
+  }
+</style>
 <script>
 export default {
   data() {

examples/docs/zh-CN/input.md

@@ -341,6 +341,11 @@ export default {
     <el-button slot="append" icon="search"></el-button>
   </el-input>
 </div>
+<style>
+  .el-select .el-input {
+    width: 110px;
+  }
+</style>
 <script>
 export default {
   data() {