README: specify that Docker images are available for amd64 and arm64

* finalrewind.org APT repository for Debian-based distributions

* Installing the latest release from CPAN

* Installation from source

* Using a Docker image

* Using a Docker image (amd64 or arm64)

Except for Docker, __dbris__ is available in your PATH after installation.

You can run `dbris --version` to verify this. Documentation is available via

### Running dbris via Docker

A dbris image is available on Docker Hub. It is intended for testing purposes:

due to the latencies involved in spawning a container for each dbris invocation

and lack of caching, it is less convenient for day-to-day usage.

**dbris** images for amd64 and arm64 are available on Docker Hub.

They are intended for testing purposes:

due to the latencies involved in spawning a container for each dbris invocation and lack of caching, they are less convenient for day-to-day use.

Installation:

docker pull derfnull/dbris:latest

```

Use it by prefixing dbris commands with `docker run --rm

derfnull/dbris:latest`, like so:

Use the image by prefixing dbris commands with `docker run --rm derfnull/dbris:latest`, like so:

```

docker run --rm derfnull/dbris:latest --version