added note to upgrade procedures about enabling api auditing

content/rancher/v2.x/en/upgrades/upgrades/ha-server-upgrade/_index.md

@@ -17,6 +17,8 @@ To upgrade Rancher 2.x running in a high availability configuration, run an upgr
 
 1. Change directory to the location of the RKE binary. Your `rancher-cluster.yml` file must reside in the same directory.
 
+     >**Note:** Before upgrade, you can configure `rancher-cluster.yml` to enable API Auditing, which records all interactions with the Rancher API. For more information, see [RKE Documentation: API Auditing]({{< baseurl >}}\rke\v0.1.x\en\config-options\add-ons\api-auditing).
+
 1. <a id="snapshot"></a> Enter the following command. Replace `<SNAPSHOT.db>` with any name that you want to use for the snapshot (e.g. `upgrade.db`).
 
     ```

content/rancher/v2.x/en/upgrades/upgrades/single-node-upgrade/_index.md

@@ -55,6 +55,16 @@ docker pull rancher/rancher:latest
 docker run -d --volumes-from rancher-data --restart=unless-stopped \
 -p 80:80 -p 443:443 rancher/rancher:latest
     ```
+    >**Note:** When entering the command to upgrade Rancher, you can declare additional flags to enable [API Auditing]({{< baseurl >}}/rancher/v2.x/en/installation/api-auditing), which records all interactions with the Rancher API. If you want to enable API Auditing, append the following flags to your upgrade command:
+>
+>```
+-e AUDIT_LEVEL=1 \
+-e AUDIT_LOG_PATH=/var/log/auditlog/rancher-api-audit.log \
+-e AUDIT_LOG_MAXAGE=20 \
+-e AUDIT_LOG_MAXBACKUP=20 \
+-e AUDIT_LOG_MAXSIZE=100 \
+```
+    
     >**Note:** _Do not_ stop the upgrade after initiating it, even if the upgrade process seems longer than expected. Stopping the upgrade may result in database migration errors during future upgrades.
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