Document the 'unwind' removal.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149914 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/ReleaseNotes.html b/docs/ReleaseNotes.html
index b090995..71b7148 100644
--- a/docs/ReleaseNotes.html
+++ b/docs/ReleaseNotes.html
@@ -285,7 +285,10 @@
 
   <ul>
     <li>IR support for half float</li>
-	<li>IR support for vectors of pointers, including vector GEPs.</li>
+    <li>IR support for vectors of pointers, including vector GEPs.</li>
+    <li>The <tt>unwind</tt> instruction is now gone. It has been replaced by
+        the <tt>landingpad</tt>/<tt>resume</tt> exception handling
+        mechanisms.</li>
     <li>....</li>
   </ul>
 </div>