Update getting started to refer to docker image

[jackgerrits]

We release an alpine based docker image for each tagged release but this is not listed on the getting started page and so it is hard for people to find out about it.

https://hub.docker.com/r/vowpalwabbit/vw-rel-alpine

[moksh-pathak]

Hi, I would like to work on this, can it assigned to me?

[jackgerrits]

Sure. I think the plan for this one would be to add another layer to the selector which corresponds to "method". The docker image is only relevant for the command line package. Therefore, the available methods all command would change to "source" and "docker". The existing brew instruction for MacOS should change to a brew "method" and a source method should be added for MacOS along side it.

Here's a rough sketch of what it may look like for the Windows target.

The relevant files for the getting started page are here:

• https://github.com/VowpalWabbit/vowpalwabbit.github.io/blob/source/assets/js/install_vw.js
• https://github.com/VowpalWabbit/vowpalwabbit.github.io/blob/source/_includes/install_vw.html
• https://github.com/VowpalWabbit/vowpalwabbit.github.io/blob/source/_sass/_install_vw.scss

[moksh-pathak]

Thanks, I'm on it.