[SPARK-30363]Add Documentation for refresh resources.

Author: iRakson

docs/_data/menu-sql.yaml

@@ -216,6 +216,8 @@
                   url: sql-ref-syntax-aux-resource-mgmt-list-file.html
                 - text: LIST JAR
                   url: sql-ref-syntax-aux-resource-mgmt-list-jar.html
+                - text: REFRESH
+                  url: sql-ref-syntax-aux-resource-mgmt-refresh.md
     - text: Functions
       url: sql-ref-functions.html
       subitems:

docs/sql-ref-syntax-aux-resource-mgmt-refresh.md

@@ -0,0 +1,49 @@
+---
+layout: global
+title: REFRESH
+displayTitle: REFRESH
+license: |
+  Licensed to the Apache Software Foundation (ASF) under one or more
+  contributor license agreements.  See the NOTICE file distributed with
+  this work for additional information regarding copyright ownership.
+  The ASF licenses this file to You under the Apache License, Version 2.0
+  (the "License"); you may not use this file except in compliance with
+  the License.  You may obtain a copy of the License at
+ 
+     http://www.apache.org/licenses/LICENSE-2.0
+ 
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+---
+
+### Description
+`REFRESH` is used to invalidate and refresh all the cached data (and the associated metadata) for
+all Dataset, that contains the given data source path. Path matching is by prefix, i.e. "/" would 
+invalidate everything that is cached.
+
+### Syntax
+{% highlight sql %}
+REFRESH resource_name
+{% endhighlight %}
+
+### Parameters
+<dl>
+ <dt><code><em>resource_name</em></code></dt>
+ <dd>The path of the resource that is to be refreshed.</dd>
+</dl>
+
+### Examples
+{% highlight sql %}
+REFRESH /tmp/test.jar;
+REFRESH "/tmp/test.txt";
+REFRESH '/tmp/test.txt';
+{% endhighlight %}
+
+### Related Statements
+ * [LIST JAR](sql-ref-syntax-aux-resource-mgmt-list-jar.html)
+ * [ADD FILE](sql-ref-syntax-aux-resource-mgmt-add-file.html)
+ * [LIST FILE](sql-ref-syntax-aux-resource-mgmt-list-file.html)
+ * [ADD JAR](sql-ref-syntax-aux-resource-mgmt-add-jar.html)