Move Docker image distribution to its own repo

[fnando]

What

Removes the Dockerfile, its entrypoint.sh, the docker/README.md (Docker Hub description), and the docker.yml workflow that built and published CLI images. Adds a note to the README's Install section pointing users to the dedicated stellar/stellar-cli-docker repository and Docker Hub.

Why

Docker image building and distribution is now owned by the stellar/stellar-cli-docker repository, so keeping the Dockerfile and publishing workflow here is redundant and risks the two drifting apart. Centralizing it in one place keeps the source of truth clear.

Known limitations

N/A — the ledger-emulator.yml workflow and the stellar container command still use Docker as a runtime and are unaffected; only image publishing was removed.

[Copilot]

Pull request overview

This PR removes Docker image build/publish assets from stellar/stellar-cli and updates user-facing documentation to point to the dedicated Docker distribution repository (stellar/stellar-cli-docker) and Docker Hub.

Changes:

• Added a Docker run snippet and pointers to the new Docker distribution repo + Docker Hub in the main README.
• Removed the legacy Docker build recipe and entrypoint script from this repository.
• Deleted the GitHub Actions workflow that built/published Docker images and updated the Docker Hub description.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
README.md	Documents how to run the CLI via Docker and links users to the new source-of-truth repo and Docker Hub.
entrypoint.sh	Removes the Docker entrypoint script now owned by the separate Docker distribution repo.
Dockerfile	Removes the Docker image build recipe from this repo to prevent drift with the new distribution repo.
docker/README.md	Removes the Docker Hub description content that was previously maintained here.
.github/workflows/docker.yml	Removes the Docker image build/publish workflow now handled elsewhere.