Added 'remove' documentation to 'readme.md'

Author: Sergio Abreu García

readme.md

@@ -227,6 +227,22 @@ ghpages.publish('dist', {
 }, callback);
 ```
 
+#### <a id="optionsuser">options.remove</a>
+ * type: `string`
+ * default: `'.'`
+
+Removes files that match the given pattern (Ignored if used together with
+`--add`). By default, `gh-pages` removes everything inside the target branch
+auto-generated directory before copying the new files from `dir`.
+
+Example use of the `remove` option:
+
+```js
+ghpages.publish('dist', {
+  remove: "*.json"
+}, callback);
+```
+
 
 #### <a id="optionspush">options.push</a>
  * type: `boolean`
@@ -325,7 +341,7 @@ Note that this plugin requires Git 1.9 or higher (because it uses the `--exit-co
   ```
 
 When processing `gh-pages` module generate file in`.cache/` and if stuck some reason like wrong password
-it will not automatically cleanup 
+it will not automatically cleanup
 
 Run `~node_modules/gh-pages/bin/gh-pages-clean`
 or remove `~node_modules/gh-pages/.cache`