Remove outdated "extras" section in with-tailwindcss example README

[xstevenyung]

Hello there !

Thanks for the amazing work !

The Extras section in the README from with-tailwindcss example is outdated as all the commands mentioned are no longer in the package.json like stated.

This commit just removed those.

Cheers !

[github-actions]

Stats from current PR

Click to expand stats

	zeit/next.js canary	stvnyung/next.js canary	Change
Build Duration	15.3s	14.9s	-331ms
node_modules Size	40.1 MB	40.1 MB	⚠️ +16 B
Total Bundle (main, webpack, commons) Size	209 kB	209 kB	✓
Total Bundle (main, webpack, commons) gzip Size	68.3 kB	68.3 kB	✓
Client _app Size	2.54 kB	2.54 kB	✓
Client _app gzip Size	1.05 kB	1.05 kB	✓
Client _error Size	8.19 kB	8.19 kB	✓
Client _error gzip Size	3.12 kB	3.12 kB	✓
Client pages/index Size	288 B	288 B	✓
Client pages/index gzip Size	222 B	222 B	✓
Client pages/link Size	4.83 kB	4.83 kB	✓
Client pages/link gzip Size	2.11 kB	2.11 kB	✓
Client pages/routerDirect Size	411 B	411 B	✓
Client pages/routerDirect gzip Size	296 B	296 B	✓
Client pages/withRouter Size	393 B	393 B	✓
Client pages/withRouter gzip Size	280 B	280 B	✓
Client main Size	23.3 kB	23.3 kB	✓
Client main gzip Size	7.63 kB	7.63 kB	✓
Client commons Size	183 kB	183 kB	✓
Client commons gzip Size	59.4 kB	59.4 kB	✓
Client webpack Size	1.49 kB	1.49 kB	✓
Client webpack gzip Size	769 B	769 B	✓
Base Rendered Size	1.34 kB	1.34 kB	✓
Build Dir Size	801 kB	801 kB	✓

Click to expand serverless stats

	zeit/next.js canary	stvnyung/next.js canary	Change
Build Duration	16.2s	16.3s	⚠️ +74ms
node_modules Size	40.1 MB	40.1 MB	⚠️ +16 B
Total Bundle (main, webpack, commons) Size	209 kB	209 kB	✓
Total Bundle (main, webpack, commons) gzip Size	68.3 kB	68.3 kB	✓
Client _app Size	2.54 kB	2.54 kB	✓
Client _app gzip Size	1.05 kB	1.05 kB	✓
Client _error Size	8.19 kB	8.19 kB	✓
Client _error gzip Size	3.12 kB	3.12 kB	✓
Client pages/index Size	288 B	288 B	✓
Client pages/index gzip Size	222 B	222 B	✓
Client pages/link Size	4.83 kB	4.83 kB	✓
Client pages/link gzip Size	2.11 kB	2.11 kB	✓
Client pages/routerDirect Size	411 B	411 B	✓
Client pages/routerDirect gzip Size	296 B	296 B	✓
Client pages/withRouter Size	393 B	393 B	✓
Client pages/withRouter gzip Size	280 B	280 B	✓
Client main Size	23.3 kB	23.3 kB	✓
Client main gzip Size	7.63 kB	7.63 kB	✓
Client commons Size	183 kB	183 kB	✓
Client commons gzip Size	59.4 kB	59.4 kB	✓
Client webpack Size	1.49 kB	1.49 kB	✓
Client webpack gzip Size	769 B	769 B	✓
Serverless pages/link Size	342 kB	342 kB	✓
Serverless pages/link gzip Size	88.7 kB	88.7 kB	-1 B
Serverless pages/index Size	333 kB	333 kB	✓
Serverless pages/index gzip Size	86.3 kB	86.3 kB	✓
Serverless pages/_error Size	334 kB	334 kB	✓
Serverless pages/_error gzip Size	86.1 kB	86.1 kB	✓
Serverless pages/routerDirect Size	333 kB	333 kB	✓
Serverless pages/routerDirect gzip Size	86.3 kB	86.3 kB	✓
Serverless pages/withRouter Size	333 kB	333 kB	✓
Serverless pages/withRouter gzip Size	86.4 kB	86.4 kB	✓
Build Dir Size	2.37 MB	2.37 MB	✓

[timneutkens]

Looks fine to me!