[css-cascade] Add level additions section. Fixes w3c#617

Author: fantasai

css-cascade-3/Overview.bs

@@ -882,6 +882,19 @@ Changes Since the 3 October 2013 Candidate Recommendation</h3>
 
 	<p>A <a href="https://drafts.csswg.org/css-cascade-3/issues-cr-2013">Disposition of Comments</a> is available.
 
+
+<h3 id="changes-2">
+Additions to Level 2</h3>
+
+	The following features have been added since
+	<a href="http://www.w3.org/TR/CSS2/cascade.html">Level 2</a>:
+
+	<ul>
+		<li>The 'all' shorthand
+		<li>The ''unset'' keyword
+		<li>Incorporation of scoped styles, animations, and transitions into the <a>cascade</a>.
+	</ul>
+
 <h2 class="no-num" id="acknowledgments">Acknowledgments</h2>
 
 	David Baron, Simon Sapin, and Boris Zbarsky contributed to this specification.

css-cascade/Overview.bs

@@ -977,12 +977,25 @@ Changes</h2>
 <h3 id="additions-l3">
 Additions Since Level 3</h3>
 
-	The following additions were made to this specification since the
-	<a href="https://www.w3.org/TR/css-cascade-3/">Level 3 CR</a>:
+	The following features have been added since
+	<a href="https://www.w3.org/TR/css-cascade-3/">Level 3</a>:
 
 	* Introduced ''revert'' keyword, for rolling back the cascade.
 	* Introduced ''supports()'' syntax for supports-conditional ''@import'' rules.
 
+
+<h3 id="changes-2">
+Additions to Level 2</h3>
+
+	The following features have been added since
+	<a href="http://www.w3.org/TR/CSS2/cascade.html">Level 2</a>:
+
+	<ul>
+		<li>The 'all' shorthand
+		<li>The ''unset'' keyword
+		<li>Incorporation of scoped styles, animations, and transitions into the <a>cascade</a>.
+	</ul>
+
 <h2 class="no-num" id="acknowledgments">Acknowledgments</h2>
 
 	David Baron, Tantek Çelik, Simon Sapin, and Boris Zbarsky contributed to this specification.