Update README.md to reflect a valid docker tag

[jmfernandez]

I have just tried following the steps from https://github.com/ga4gh/ga4gh-starter-kit-drs/blob/develop/README.md to pull the default docker image for this starter kit. But the first step did not work. When I tried next:

jfernan1@bsclife013[1]:~> docker pull ga4gh/ga4gh-starter-kit-drs:latest
Error response from daemon: manifest for ga4gh/ga4gh-starter-kit-drs:latest not found: manifest unknown: manifest unknown

I first checked whether I mistyped the name of the image. As it was right, then I went to https://hub.docker.com/r/ga4gh/ga4gh-starter-kit-drs/tags , and I realized latest tag does not exist.

So, could you either fix the documentation or create the image tag in Docker Hub, please?

Thanks in advance!

[yash-puligundla]

Thank you for raising the issue @jmfernandez We will update our documentation.