fix(www): Plugin library scrollbar issue (#11773)
fix(www): Plugin library scrollbar issue (#11773)

* fix(www): Don’t set `display` CSS prop to empty string/false

* fix(www): Horiz. scrollbars for plugins page sidebar on small devices

gatsbyjs/gatsby,gatsbyjs/gatsby,ChristopherBiscardi/gatsby,ChristopherBiscardi/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby