doc: update container documentation

Author: kwvg

contrib/containers/README.md

@@ -1,27 +1,33 @@
 ## Containers
 
-This directory contains configuration files for containerization utilities.
+This directory contains configuration files for containers. Containers that depends on other containers require BuildKit to
+be enabled in order for syntax extensions to work correctly.
 
-Currently two Docker containers exist, `ci` defines how Dash's GitLab CI container is built and the `dev` builds on top of the `ci` to provide a containerized development environment that is as close as possible to CI for contributors! See also [Dash on Docker Hub](https://hub.docker.com/u/dashpay) i.e. for the [dashd container](https://hub.docker.com/r/dashpay/dashd).
+| Name      | Depends On | Purpose                                                                    |
+| --------- | -----------| -------------------------------------------------------------------------- |
+| `ci-slim` | None       | Slimmed down container used to run functional tests and (some) linters     |
+| `ci`      | `ci-slim`  | Full container used to (cross) compile                                     |
+| `develop` | `ci`       | Interactive environment to allow debugging in an environment that's 1:1 CI |
+| `deploy`  | None       | Packaging of builds for release on Docker Hub                              |
+| `guix`    | None       | Interactive environment for building (and packaging) with Guix             |
 
 ### Usage Guide
 
-We utilise edrevo's [dockerfile-plus](https://github.com/edrevo/dockerfile-plus), a syntax extension that
-leverages Docker [BuildKit](https://docs.docker.com/develop/develop-images/build_enhancements/) to reduce
+We utilise edrevo's [devthefuture/dockerfile-x](https://codeberg.org/devthefuture/dockerfile-x), a syntax extension that
+leverages Docker [BuildKit](https://docs.docker.com/build/buildkit/) to reduce
 the amount of repetitive code.
 
-As BuildKit is opt-in within many currently supported versions of Docker (as of this writing), you need to
-set the following environment variables before continuing. While not needed after the initial `docker compose build`
-(barring updates to the `Dockerfile`), we recommend placing this in your `~/.bash_profile`/`~/.zshrc` or equivalent
+As BuildKit is opt-in within some versions of Docker, you may need to set the following environment variables before
+continuing. While not needed after the initial `docker compose build` (barring updates to the `Dockerfile`), we
+recommend placing this in your `~/.bash_profile`/`~/.zshrc` or equivalent
 
 ```bash
 export DOCKER_BUILDKIT=1
 export COMPOSE_DOCKER_CLI_BUILD=1
 ```
 
-After that, it's simply a matter of building and running your own development container. You can use extensions
-for your IDE like Visual Studio Code's [Remote Containers](https://code.visualstudio.com/docs/remote/containers)
-to run terminal commands from inside the terminal and build Dash Core.
+You can use extensions for your IDE like Visual Studio Code's [Remote Containers](https://code.visualstudio.com/docs/remote/containers)
+to run terminal commands from inside the terminal and work with Dash Core.
 
 ```bash
 cd contrib/containers/develop