* simplify installation steps
Since docusaurus-init is run seldomly, npx keeps it simpler,
and subsequent runs will be using the latest version.
Outdated provides more meaningful view of current and latest version
* add more doc on who can use npx
* Make yarn and npm commands more specific
Change
> Docusaurus was designed from the ground up to be easily installed and used to get your website up **an** running quickly.
to
> Docusaurus was designed from the ground up to be easily installed and used to get your website up **and** running quickly.
