Updated link to single cell course

[sjspielman]

Updated the broken link to address #518.

The updated file is an md, not Rmd, so I'm not sure if it should be re-rendered but assuming not(?). For now did not re-render, but can!

[jashapiro]

The updated file is an md, not Rmd, so I'm not sure if it should be re-rendered but assuming not(?). For now did not re-render, but can!

The .md files do need to be rendered manually; the list of files that will be automatically rendered is here: https://github.com/AlexsLemonade/training-modules/blob/master/scripts/render-live.sh#L18-L42]

Otherwise, looks good, but I'll wait for the render to approve.

[sjspielman]

the list of files that will be automatically rendered is here: [https://github.com/AlexsLemonade/training-modules/blob/master/scripts/render-live.sh#L18-L42]](https://github.com/AlexsLemonade/training-modules/blob/master/scripts/render-live.sh#L18-L42%5D)

Thanks!

[jashapiro]

LGTM!