[S3AG] add documentation for S3AG

Author: jxhan3

hadoop-tools/hadoop-aws/src/site/markdown/tools/hadoop-aws/s3_access_grants.md

@@ -0,0 +1,61 @@
+<!---
+  Licensed 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. See accompanying LICENSE file.
+-->
+
+# S3 Access Grants
+
+<!-- MACRO{toc|fromDepth=0|toDepth=5} -->
+
+S3 Access Grants is a credential vending service for S3 data. More information:
+* https://aws.amazon.com/s3/features/access-grants/
+
+In S3A, S3 Access Grants Plugin is used to support S3 Access Grants. More information:
+* https://github.com/aws/aws-s3-accessgrants-plugin-java-v2/
+
+
+
+## How to enable S3 Access Grants in S3A
+
+1. Add the `hadoop-aws` JAR on your classpath.
+
+1. Add the `aws-java-sdk-bundle.jar` JAR to your classpath, the minimum version is v2.23.7.
+
+2. Add the `aws-s3-accessgrants-java-plugin-2.0.0.jar` JAR to your classpath.
+3. Add the `caffeine.jar` JAR to your classpath.
+
+1. Add configurations to enable S3 Access Grants in `core-site.xml`
+
+
+
+Example:
+
+```xml
+<configuration>
+...
+    <property>
+        <name>fs.s3a.accessgrants.enabled</name>
+        <value>true</value>
+        <description>Enable S3 Access Grants or not</description>
+    </property>
+    <property>
+        <name>fs.s3a.accessgrants.fallbacktoiam</name>
+        <value>false</value>
+        <description>Enable IAM Policy as fallback or not</description>
+    </property>
+...
+</configuration>
+```
+
+
+
+