html: write descriptive list closing dt tag on separate line

now that i'm already looking at it due to the bug leenzhu found why not put the
</dt> on a separate line to match the convention - looks better to me; doesn't
change anything.

org/html_writer.go

@@ -335,7 +335,7 @@ func (w *HTMLWriter) WriteDescriptiveListItem(di DescriptiveListItem) {
 	} else {
 		w.WriteString("?")
 	}
-	w.WriteString("</dt>\n")
+	w.WriteString("\n</dt>\n")
 	w.WriteString("<dd>\n")
 	WriteNodes(w, di.Details...)
 	w.WriteString("</dd>\n")

org/testdata/lists.html

@@ -109,7 +109,8 @@ descriptive lists
 </p>
 <dl>
 <dt class="unchecked">
-term</dt>
+term
+</dt>
 <dd>
 <p>
 details
@@ -117,21 +118,24 @@ continued details
 </p>
 </dd>
 <dt class="unchecked">
-?</dt>
+?
+</dt>
 <dd>
 <p>
 details without a term
 </p>
 </dd>
 <dt class="checked">
-term</dt>
+term
+</dt>
 <dd>
 <p>
 details on a new line
 </p>
 </dd>
 <dt>
-term</dt>
+term
+</dt>
 <dd>
 <p>
 details on a new line (with an empty line in between)
@@ -211,14 +215,16 @@ ordered 2
 </ol>
 <dl>
 <dt>
-unordered descriptive</dt>
+unordered descriptive
+</dt>
 <dd>
 <p>
 1
 </p>
 </dd>
 <dt>
-unordered descriptive</dt>
+unordered descriptive
+</dt>
 <dd>
 <p>
 2
@@ -227,14 +233,16 @@ unordered descriptive</dt>
 </dl>
 <dl>
 <dt>
-ordered descriptive</dt>
+ordered descriptive
+</dt>
 <dd>
 <p>
 1
 </p>
 </dd>
 <dt>
-ordered descriptive</dt>
+ordered descriptive
+</dt>
 <dd>
 <p>
 2