add entry in 'changes between RDF 1.1 and RDF 1.2'

Author: pchampin

spec/index.html

@@ -2204,6 +2204,8 @@ <h3>Acknowledgments for RDF 1.2</h3>
   <h2>Changes between RDF 1.1 and RDF 1.2</h2>
 
   <ul>
+    <li>Added <a href="#section-classic-full-interop" class="sectionRef"></a>
+      for informative mappings between RDF [=Full=] and RDF [=Classic=].</li>
     <li>Added <a href="#section-dataset-quad" class="sectionRef"></a>
       for informative definition of a <a>quad</a>.</li>
    <li>Added <a href="#section-triple-terms-reification" class="sectionRef"></a>