[css-ruby] Add changes section

Author: fantasai

css-ruby/Overview.src.html

@@ -1442,6 +1442,63 @@ <h2 class=no-num id="acknowledgments">
 Pratley, Takao Suzuki(<span lang="ja">鈴木 孝雄</span>), Frank Yung-Fong Tang, Chris Thrasher, Masafumi Yabe<span lang="ja">家辺
 勝文</span>), Steve Zilles.</p>
 
+<h2 class="no-num" id="changes">
+Changes</h2>
+
+	<p>The following major changes have been made since the previous Working Draft:
+	<dl>
+		<dt>Remove 'ruby-span' and mentions of <code>rbspan</code>.
+		<dd>
+			Explicit spanning is not used in HTML ruby in favor of implicit spanning.
+			This can't handle some pathological double-sided spanning cases,
+			but there seems to be no requirement for these at the moment.
+			(For implementations that support full complex XHTML Ruby,
+			they can imply spanning from the markup the same magic way
+			that we handle cell spanning from tables. It doesn't seem
+			necessary to include controls this in Level 1.)
+
+		<dt>Defer 'ruby-overhang' and ''ruby-align: line-end'' to Level 2.
+		<dd>
+			It's somewhat complicated, advanced feature.
+			Proposal is to make this behavior UA-defined
+			and provide some examples of acceptable options.
+
+		<dt>Close issue requesting 'display: rp': use ''display: none''.
+		<dd>
+			The i18nwg added an issue requesting a display value for &lt;rp> elements.
+			They're supposed to be hidden when &tl;ruby> is displayed as ruby.
+			But this is easily accomplished already with ''display: none''.
+
+		<dt>Change 'ruby-position' values to match 'text-emphasis-position'.
+		<dd>
+			Other than ''inter-character'', which we need to keep,
+			it makes more sense to align ruby positions with 'text-emphasis-position',
+			which can correctly handle various combinations of horizontal/vertical preferences.
+
+		<dt>Remove unused values of 'ruby-align'.
+		<dd>
+			'left', 'right', and 'end' are not needed.
+
+		<dt>Added 'ruby-merge' property to control jukugo rendering.
+		<dd>
+			This is a stylistic effect, not a structural one;
+			the previous model assumed that it was structural and suggested handling it by changing markup. :(
+
+		<dt>Remove ''inline'' from 'ruby-position'.
+		<dd>
+			This is do-able via ''display: inline'' on all the ruby-related elements,
+			see <a href="#default-inline">Appendix A</a>
+
+		<dt>Added <a href="#default-style">Default Style</a> rules
+		<dd>
+			As requested by i18nwg.
+
+		<dt>Wrote anonymous box generation rules
+		<dd>
+			And defined pairing of bases and annotations.
+			Should now handle all the crazy proposed permutations of HTML ruby markup.
+	</dl>
+
 <h2 class=no-num id="references">
 References</h2>