[css-color-adjust-1] Add an intro paragraph. w3c#5897

Author: fantasai

css-color-adjust-1/Overview.bs

@@ -26,6 +26,25 @@ spec:fill-stroke-3; type:property;
 Introduction {#intro}
 =====================
 
+	This specification introduces three new features
+	related to controlling how/when colors are auto-adjusted
+	by the user agent:
+
+	* The concept of [=color schemes=]
+		and the 'color-scheme' property,
+		which controls whether or not browser-provided parts of the page's UI
+		respect the user's chosen [=color scheme=].
+
+	* The concept of [=forced colors mode=]
+		and the 'forced-color-adjust' property,
+		which controls whether or not [=forced colors mode=] is allowed to apply to a given element.
+
+	* The 'color-adjust' property,
+		which controls whether the browser is allowed
+		to automatically adjust colors to the user's assumed performance preferences,
+		such as suppressing background colors when printing to save ink.
+
+
 Value Definitions {#values}
 ---------------------------