[Feature Request]: Publish Docker images tagged with major version

### What problem does this feature solve or what does it enhance?

Certbot Docker images are currently tagged with full major.minor.patch version (`certbot/certbot:v5.6.0`) and latest (`certbot/certbot:latest`) in [Docker hub]( https://hub.docker.com/r/certbot/certbot/) but tags with major version are not available.

If someone wants to stick to a Certbot Docker image of the latest of a certain major version (a good practice to be up to date on security but avoid breaking changes) there is no way to do that without manual changes to the Docker command or non-trivial automation.

### Proposed Solution

Publish Certbot major versions with tags like `certbot/certbot:v5`, `certbot/certbot:v5.6`.

### Alternatives Considered

_No response_