doc find usefull component

• Document what-is a component on README.md

• Find usefull component to build a community

• Test them on dev server

• Document them on README.md

• Howto install a component : https://meta.discourse.org/t/how-do-i-install-a-theme-or-theme-component/63682

• List of component : https://meta.discourse.org/tag/theme-component