[css-color-4] Introduce the term colorspaces in the introduction

Author: svgeesus

css-color-4/Overview.bs

@@ -45,7 +45,9 @@ Introduction</h2>
 
 	<em>This section is not normative.</em>
 
-	This module describes CSS properties which allow authors to specify the foreground color and opacity of the text content of an element.
+	This module describes CSS properties which
+	allow authors to specify
+	the foreground color and opacity of the text content of an element.
 	This module also describes in detail the CSS <<color>> value type.
 
 
@@ -55,6 +57,18 @@ Introduction</h2>
 	and <a href="https://www.w3.org/TR/css-color-3/">CSS Color 3</a>,
 	but also defines new properties and values.
 
+	In particular, it allows specifying colors
+	in other 'colorspaces' than sRGB;
+	previously, the more saturated colors ouside the sRGB gamut
+	could not be used in CSS
+	even if the display device supported them.
+	In addition to the family of
+	<abbr title="red-green-blue">RGB</abbr> colorspaces,
+	'colorspaces' with other primaries
+	such as <abbr title="cyan-magenta-yellow-black">CMYK</abbr> or
+	<abbr title="cyan-magenta-yellow-green-orange-violet-black">CMYGOVK</abbr>
+	are supported.
+
 
 <h2 id="the-color-property">
 Foreground Color: the 'color' property</h2>