[css-transforms-2] Add changes section.

Author: dbaron

css-transforms-2/Overview.bs

@@ -1422,3 +1422,22 @@ Security and Privacy Considerations {#priv-sec}
 ===============================================
 
 This specification introduces no new security or privacy considerations.
+
+<h2 class="no-num" id="changes">
+Changes</h2>
+
+<h3 class="no-num" id="changes-recent">
+Recent Changes</h3>
+
+	Substantive changes since <a href="https://www.w3.org/TR/2020/WD-css-transforms-2-20200303/">3 March 2020 WD</a>:
+
+	<ul>
+		<li>The specification no longer requires maintaining state for whether individual transform properties have 2D or 3D values, but instead requires that any value that can be expressed as 2D is treated as 2D (see <a href="https://github.com/w3c/csswg-drafts/issues/3305">#3305</a>).</li>
+		<li>The 'scale' property and ''scale()'', ''scaleX()'' and ''scaleY()'' functions now support percentages (see <a href="https://github.com/w3c/csswg-drafts/issues/3399">#3399</a>).</li>
+		<li>Define that paint containment is a grouping property (see <a href="https://github.com/w3c/csswg-drafts/issues/6202">#6202</a>).</li>
+		<li>Add support for a ''perspective()/none'' argument to ''perspective()'' (see <a href="https://github.com/w3c/csswg-drafts/issues/6488">#6488</a>).</li>
+		<li>Define that clamping of values of ''perspective()'' also applies to resolved values and interpolation (see <a href="https://github.com/w3c/csswg-drafts/issues/6320">#6320</a> and <a href="https://github.com/w3c/csswg-drafts/issues/6346">#6346</a>).</li>
+		<li>Clarify that the effects of ''transform-style/preserve-3d'' only affect <a>transformable elements</a> (see <a href="https://github.com/w3c/csswg-drafts/issues/6430">#6430</a>).</li>
+		<li>Added a note that the resolved value of 'translate' includes percentages (see <a href="https://github.com/w3c/csswg-drafts/issues/2124">#2124</a>).</li>
+	</ul>
+