feat: Migrate docker preview repo stuff in monorepo (#25698)

* feat: Migrate docker preview repo stuff in monorepo

* docs: Update docs [skip ci]

* config: Update configuration to minimum [skip ci]

server/build/docker-preview/README.md

@@ -0,0 +1,19 @@
+# Mattermost Docker Preview Image
+
+This is a Docker image to install Mattermost in *Preview Mode* for exploring product functionality on a single machine using Docker.
+
+Note: This configuration should not be used in production, as it’s using a known password string and contains other non-production configuration settings, and it does not support upgrade. If you’re looking for a production installation with Docker, please see the [Mattermost Production Docker Deployment Guide](https://docs.mattermost.com/install/install-docker.html#deploy-mattermost-on-docker-for-production-use).
+
+To contribute, please see [Contribution Guidelines](https://developers.mattermost.com/contribute/more-info/getting-started/).
+
+To file issues, [search for existing bugs and file a GitHub issue if your bug is new](https://developers.mattermost.com/contribute/why-contribute/#youve-found-a-bug).
+
+## Usage
+
+Please see [documentation for usage](http://docs.mattermost.com/install/docker-local-machine.html).
+
+If you have Docker already set up, you can run this image in one line:
+
+```
+docker run --name mattermost-preview -d --publish 8065:8065 --add-host dockerhost:127.0.0.1 mattermost/mattermost-preview
+```