Fix CSS Guidelines website link

[heitoralthmann]

starterkit-twig-demo/dist/css/style.css

Lines 23 to 30 in e2d50b7

	* CSS Guidelines by Harry Roberts : https://github.com/csswizardry/CSS-Guidelines
	So feel free to use any of these approaches. Or don't. It's totally up to you.
	*/
	/*------------------------------------*\
	$TABLE OF CONTENTS
	based generally on Harry Roberts excellent CSS Guidelines https://github.com/csswizardry/CSS-Guidelines

Harry Roberts' CSS Guidelines website has moved to https://cssguidelin.es/

Just a fancy adjustment 😊