Update release notes to quote the new tutorial rebin.C

git-svn-id: http://root.cern.ch/svn/root/trunk@29922 27541ba8-7e3a-0410-8455-c3a389f83636

hist/doc/v526/index.html

@@ -3,10 +3,17 @@
 <a name="hist"></a> 
 <h3>Histogram package</h3>
 
-<h4>TGraphTime</h4>
+<h4>new class TGraphTime</h4>
 <ul>
 <li> <tt>TGraphTime</tt> is a new class to organize and draw a list of 
      objects evolving with time. An example of use is shown in the tutorial
      <tt>$ROOTSYS/tutorials/graphs/gtime.C</tt>.
 </ul>
 
+<h4>new tutorial rebin.C</h4>
+This tutorial illustrates how to:
+<ul>
+<li>create a variable binwidth histogram with a binning such
+   that the population per bin is about the same.
+<li>rebin a variable binwidth histogram into another one.
+</ul>