Support for Apple Silicon architecture

For reference, I found this closed issue when creating this one: #120 (closed)

We have a couple of developers here developing on Apple Silicon. The step by step instructions work out of the box except for the a d4d up step, where the following type of issue recurs for multiple required service images:

Error response from daemon: image with reference [service/name:x] was found but does not match the specified platform: wanted linux/amd64, actual: linux/arm64

To work around this I created a docker-compose.override.yml file in the project root, where I copied the entire contents of the main docker-compose.yml file (which gets overwritten on composer install) and added the platform: linux/amd64 line before the image for the services in question, namely mariadb, mariadbtest, pma and mailhog, eg:

  mariadb:
    platform: linux/amd64
    image: 'wodby/mariadb:10.6'

Once solved, the file was shared with another Apple Silicon based developer (on a different project), and they were also able to install successfully.

This hint came from stackoverflow.

So the linux/amd64 version of the images in question are explicitly requested. At some point I expect arm64 variants will be released and they will have better performance, so I wouldn't suggest committing this fix in the repo. But this could be useful on a FAQ/Troubleshooting/Documentation page for Apple Silicon users.