[css-inline] add section on initial letter punctuation

Author: dauwhe

css-inline/Overview.bs

@@ -402,6 +402,18 @@ Raised Initial Letters</h4>
 	</pre>
 	</div>
 
+<h4 id="initial-letter-punctuation">Initial Letter Punctuation</h4>
+
+Since <code>::first-letter</code> selects punctuation before or after the first letter, these characters are included in the initial-letter. 
+
+	<figure>
+		<img src="images/initial-letter-punctuation-quote.png" width="604"
+		     alt="Paragraph showing both opening quote and first letter set as three-line drop cap">
+		<figcaption>The <code>::first-letter</code> pseudo-element selects the quotation mark as well as the “M.”</figcaption>
+	</figure>
+
+	Issue: Should there be a way to opt out of this behavior? See <a href="https://github.com/w3c/csswg-drafts/issues/310">Github Issue 310</a>.
+
 <h3 id="sizing-drop-initials">
 Creating Initial Letters: the 'initial-letter' property</h3>