Restructure README

[ludeeus]

Brings the action to the top, and adds the arguments.

Should we wrap it in <details>?

Example:

Expand to see all the arguments

Options:
-h, --help
      Display this help and exit.

Repository / Data
  -r, --repository <REPOSITORY>
      Set git repository to load data from.
  -b, --branch <BRANCH>
      Set git branch for repository.
  -t, --target <PATH_TO_BUILD>
      Set local folder or path inside repository for build.

Version/Image handling
  -v, --version <VERSION>
      Overwrite version/tag of build.
  -i, --image <IMAGE_NAME>
      Overwrite image name of build / support {arch}.
  --release <VERSION>
      Additional version information like for base images.
  --release-tag
      Use this as main tag.

Architecture
  --armhf
      Build for arm v6.
  --armv7
      Build for arm v7.
  --amd64
      Build for intel/amd 64bit.
  --aarch64
      Build for arm 64bit.
  --i386
      Build for intel/amd 32bit.
  --all
      Build all architecture.

Build handling
  --test
      Disable push to dockerhub.
  --no-latest
      Do not tag images as latest.
  --no-cache
      Disable cache for the build (from latest).
  --self-cache
      Use same tag as cache tag instead latest.
  --cache-tag
      Use a custom tag for the build cache.
  -d, --docker-hub <DOCKER_REPOSITORY>
      Set or overwrite the docker repository.
  --docker-hub-check
      Check if the version already exists before starting the build.
  --docker-user
      Username to login into docker with
  --docker-password
      Password to login into docker with
  --no-crossbuild-cleanup
      Don't cleanup the crosscompile feature (for multiple builds)

  Use the host docker socket if mapped into container:
      /var/run/docker.sock

Internals:
  --addon
      Default on. Run all things for an addon build.
  --generic <VERSION>
      Build based on the build.json
  --builder-wheels <PYTHON_TAG>
      Build the wheels builder for Home Assistant.
  --base <VERSION>
      Build our base images.
  --base-python <VERSION=ALPINE>
      Build our base python images.
  --base-raspbian <VERSION>
      Build our base raspbian images.
  --base-ubuntu <VERSION>
      Build our base ubuntu images.
  --base-debian <VERSION>
      Build our base debian images.
  --homeassisant-landingpage
      Build the landingpage for machines.
  --homeassistant-machine <VERSION=ALL,X,Y>
      Build the machine based image for a release.

[pvizeli]

Not sure. Maybe later?

[frenck]

Added some suggestions to make longer commands more readable and remove the $ to avoid copy paste errors (and make it consistent).