Add idl-index appendix.

Author: gkellogg

spec/latest/json-ld-api/index.html

@@ -4290,6 +4290,9 @@ <h4>JsonLdErrorCode</h4>
   </section> <!-- end of Error Handling -->
 </section> <!-- end of The Application Programming Interfaces -->
 
+<section id="idl-index" class="appendix informative">
+</section>
+
 <section class="appendix informative">
   <h2>Changes since 1.0 Recommendation of 16 January 2014</h2>
   <ul>

spec/latest/json-ld-framing/index.html

@@ -1410,6 +1410,9 @@ <h3>application/ld-frame+json</h3>
 
 </section>
 
+<section id="idl-index" class="appendix informative">
+</section>
+
 <section class="appendix informative">
   <h2>Changes since 1.0 Draft of 30 August 2012</h2>
   <ul>