Display package description rather than summary

[RRosio]

This PR adds a conditional to grab the package description unless it is empty, in which case the summary is pulled. It also cuts the description with an ellipsis but keeps the full description in the tooltip

[github-actions[bot]]

:point_left: Launch a binder notebook on the branch RRosio/gator/fix_pkg_descriptions

[RRosio]

For some packages, it does look like the summary is more concise and maybe better suited here... but in other cases it might be the description that provides a more helpful idea of the package functionality...