Make mosdef-workflows easier to find

To my knowledge, [mosdef-workflows](https://github.com/mosdef-hub/mosdef-workflows), isn't linked anywhere on this page. It could be nice to have a little blurb about examples of using mosdef with various engines and a link to these tutorials.

or maybe it should be linked in [mosdef_tutorials](https://github.com/mosdef-hub/mosdef_tutorials)?