Editorial: Tweaks re UTCOffset (#2933)

Add a "Syntax" header for the defining emu-grammar,
and in Annex A, add references to the new productions.

spec.html

@@ -32605,6 +32605,7 @@ <h1>Time Zone Offset String Format</h1>
           </table>
         </emu-table>
 
+        <h2>Syntax</h2>
         <emu-grammar type="definition">
           UTCOffset :::
             TemporalSign Hour
@@ -47362,6 +47363,19 @@ <h1>Number Conversions</h1>
     <emu-prodref name="StrIntegerLiteral"></emu-prodref>
   </emu-annex>
 
+  <emu-annex id="sec-time-zone-offset-string-format">
+    <h1>Time Zone Offset String Format</h1>
+    <emu-prodref name="UTCOffset"></emu-prodref>
+    <emu-prodref name="TemporalSign"></emu-prodref>
+    <emu-prodref name="ASCIISign"></emu-prodref>
+    <emu-prodref name="Hour"></emu-prodref>
+    <emu-prodref name="HourSubcomponents"></emu-prodref>
+    <emu-prodref name="TimeSeparator"></emu-prodref>
+    <emu-prodref name="MinuteSecond"></emu-prodref>
+    <emu-prodref name="TemporalDecimalFraction"></emu-prodref>
+    <emu-prodref name="TemporalDecimalSeparator"></emu-prodref>
+  </emu-annex>
+
   <emu-annex id="sec-regular-expressions">
     <h1>Regular Expressions</h1>
     <emu-prodref name="Pattern"></emu-prodref>