Add rate limiting configuration to clustering settings

Author: jasonblais

source/deployment/cluster.rst

@@ -20,6 +20,7 @@ This documentation provides a deployment guide, configuration and compatibility
  - `Mattermost Server <https://docs.mattermost.com/deployment/cluster.html#mattermost-server-configuration>`_ - Configure the cluster settings for the Mattermost application server. 
  - `Proxy Server <https://docs.mattermost.com/deployment/cluster.html#proxy-server-configuration>`_ - Configure NGINX or another load balancer to proxy servers in the cluster.
  - `File Storage Location <https://docs.mattermost.com/deployment/cluster.html#file-storage-configuration>`_ - Configure the file storage location to be compatible with a high availability setup.
+ - `Rate Limiting <https://docs.mattermost.com/deployment/cluster.html#rate-limiting>`_ - Configure recommended rate limiting settings for a high availability setup.
  - `Database <https://docs.mattermost.com/deployment/cluster.html#database-configuration>`_ - Size and deploy a multi-database configuration for high availability and scaling.
 
 - `Troubleshooting <https://docs.mattermost.com/deployment/cluster.html#id14>`_ - **Advice on troubleshooting your high availability setup.**
@@ -146,6 +147,19 @@ If you’re using the Compliance Reports feature in Enterprise Edition E20, you
 
 Migrating to NAS or S3 from local storage is beyond the scope of this document.
 
+Rate Limiting Configuration
+----------------------------------------
+
+It is recommended to enable rate limiting with the following configuration settings:
+
+ - **Maximum Queries per Second**: 10
+ - **Maximum Burst Size**: 100
+ - **Memory Store Size**: Set to the number of users in the system
+ - **Vary rate limit by remote address**: Set to ``true`` if you're using a proxy
+ - **Vary rate limit by HTTP header**: Set to ``true`` if you're using a proxy
+
+Please refer to our `Configuration Settings documentation <https://docs.mattermost.com/administration/config-settings.html#rate-limiting>`_ for more details on these settings.
+
 Database Configuration
 ------------------------------------
 Scaling the database can be accomplished by utilizing the read-replica feature. The Mattermost server can be set up to use one "master" database and up to 8 read replica databases. Mattermost distributes read requests across all databases, and sends write requests to the master database, and those changes are then sent to update the read replicas.