docs(ha): wording update when using redis

Because it is now possible to use redis as a backend locking DB for Atlantis, this FAQ should be updated.

runatlantis.io/docs/faq.md

@@ -13,7 +13,7 @@ Terraform locking can be used alongside Atlantis locking since Atlantis is simpl
 
 A: Atlantis server can easily be run under the supervision of a init system like `upstart` or `systemd` to make sure `atlantis server` is always running.
 
-Atlantis currently stores all locking and Terraform plans locally on disk under the `--data-dir` directory (defaults to `~/.atlantis`). Because of this there is currently no way to run two or more Atlantis instances concurrently.
+Atlantis, by default, stores all locking and Terraform plans locally on disk under the `--data-dir` directory (defaults to `~/.atlantis`). If you are planning to run multiple Atlantis hosts (utilizing a shared redis backend), you will want to make sure that the `data-dir` is using a shared filesystem between hosts.
 
 However, if you were to lose the data, all you would need to do is run `atlantis plan` again on the pull requests that are open. If someone tries to run `atlantis apply` after the data has been lost then they will get an error back, so they will have to re-plan anyway.
 
@@ -25,4 +25,4 @@ See `atlantis server --help` for more information.
 
 **Q: How can I get Atlantis up and running on AWS?**
 
-A: There is [terraform-aws-atlantis](https://github.com/terraform-aws-modules/terraform-aws-atlantis) project where complete Terraform configurations for running Atlantis on AWS Fargate are hosted. Tested and maintained.
+A: There is [terraform-aws-atlantis](https://github.com/terraform-aws-modules/terraform-aws-atlantis) project where complete Terraform configurations for running Atlantis on AWS Fargate are hosted. Tested and maintained.