Update new website command in getting started

[namanlp]

Hi, I know from your previous comment that this library is unmaintained, but I still want to contribute as much as I can.

In this commit, I want to update website. Actually, the current command uses very old version of Gatsby and npx. And also links to https://github.com/gregberge/smooth-doc-starter , which is unmaintained since 2020, instead of smooth-doc.

Also, user have to manually install eslint, if not installed, which users can guess themselves from error thrown.

And this commit has been thoroughly tested, so don't worry.

Thank You!