Added example commands and note about versions and the ECR repo (open…

…search-project#824)

Signed-off-by: jeffhuss <jeffhuss@amazon.com>

_opensearch/install/docker.md

@@ -7,13 +7,23 @@ nav_order: 3
 
 # Docker image
 
-You can pull the OpenSearch Docker image just like any other image:
+You can pull the OpenSearch Docker image from either Docker Hub or the public gallery hosted on AWS Elastic Container Registry (ECR).
 
+From [Docker Hub](https://hub.docker.com/u/opensearchproject):
 ```bash
 docker pull opensearchproject/opensearch:latest
 docker pull opensearchproject/opensearch-dashboards:latest
 ```
 
+From [AWS ECR](https://gallery.ecr.aws/opensearchproject/):
+```bash
+docker pull public.ecr.aws/opensearchproject/opensearch:latest
+docker pull public.ecr.aws/opensearchproject/opensearch-dashboards:latest
+```
+
+To download a specific version of OpenSearch or OpenSearch Dashboards, modify the image tag (`latest`) to point to a valid version number. For example, `docker pull opensearchproject/opensearch:1.3.0` will download the image corresponding to OpenSearch 1.3.0.
+{: .note}
+
 To check available versions, see [Docker Hub](https://hub.docker.com/u/opensearchproject).
 
 OpenSearch images use `amazonlinux:2` as the base image. If you run Docker locally, set Docker to use at least 4 GB of RAM in **Preferences** > **Resources**.
@@ -383,4 +393,4 @@ networks:
 The environment variable `"DISABLE_SECURITY_DASHBOARDS_PLUGIN=true"` disables the security dashboards plugin in OpenSearch Dashboards by removing the security dashboards plugin folder, removing all related settings in the `opensearch_dashboards.yml` file, and setting the `opensearch.hosts` entry protocol from HTTPS to HTTP.
 You can't reverse this step as the security dashboards plugin is removed in the process.
 To re-enable security for OpenSearch Dashboards, start a new container and set `DISABLE_SECURITY_DASHBOARDS_PLUGIN` to false or leave it unset.
-{: .note}
+{: .note}