* feat : #1084 Collapsus - The Collapsible Menu
* updated docs
* fixed prettier
* fix for category not auto-expanding upon navigating to a subcategory under it
* as requested by endiliey. Do not merge this commit.
* Update api-site-config.md
* Update guides-navigation.md
* Update SideNav.js
* Update main.css
* Update SideNav.js
* Delete subcategory1.md
* Delete subcategory2.md
* Update sidebars.json
* Add ability to specify sub categories in sidebar.json
* move v1 files to correct place
* refactor implementation
* refactor naming for implementation clarity