patch docs for multiselect filter

docs/migration.md

@@ -88,7 +88,7 @@ Please see [available filter configuration](https://react-bootstrap-table.github
 - [x] Custom Select Filter
 - [X] Number Filter
 - [X] Date Filter
-- [ ] Array Filter
+- [X] Array Filter
 - [X] Programmatically Filter
 
 Remember to install [`react-bootstrap-table2-filter`](https://www.npmjs.com/package/react-bootstrap-table2-filter) firstly.   

packages/react-bootstrap-table2-filter/README.md

@@ -18,6 +18,7 @@ You can get all types of filters via import and these filters are a factory func
 
 * TextFilter
 * SelectFilter
+* MultiSelectFilter
 * NumberFilter
 * DateFilter
 * CustomFilter
@@ -114,6 +115,52 @@ const qualityFilter = selectFilter({
 // omit...
 ```
 
+## MultiSelect Filter
+
+A quick example: 
+
+```js
+import filterFactory, { multiSelectFilter } from 'react-bootstrap-table2-filter';
+
+// omit...
+const selectOptions = {
+  0: 'good',
+  1: 'Bad',
+  2: 'unknown'
+};
+
+const columns = [
+  ..., {
+  dataField: 'quality',
+  text: 'Product Quailty',
+  formatter: cell => selectOptions[cell],
+  filter: multiSelectFilter({
+    options: selectOptions
+  })
+}];
+
+<BootstrapTable keyField='id' data={ products } columns={ columns } filter={ filterFactory() } />
+```
+
+Following is an example for custom select filter:
+
+```js
+import filterFactory, { multiSelectFilter, Comparator } from 'react-bootstrap-table2-filter';
+// omit...
+
+const qualityFilter = multiSelectFilter({
+  options: selectOptions,
+  placeholder: 'My Custom PlaceHolder',  // custom the input placeholder
+  className: 'my-custom-text-filter', // custom classname on input
+  defaultValue: '2', // default filtering value
+  comparator: Comparator.LIKE, // default is Comparator.EQ
+  style: { ... }, // your custom styles on input
+  withoutEmptyOption: true  // hide the default select option
+});
+
+// omit...
+```
+
 ## Number Filter
 
 ```js