update CHANGES.html and RELEASE_NOTES for random variable merge

CHANGES.html

@@ -48,12 +48,24 @@ <h1>Changes from ns-3.14 to ns-3.15</h1>
 
 <h2>New API:</h2>
 <ul>
-<li></li>
+<li>A RandomVariableStreamHelper has been introduced to assist with 
+using the Config subsystem path names to assign fixed stream numbers
+to RandomVariableStream objects.</li>
 </ul>
 
 <h2>Changes to existing API:</h2>
 <ul>
-<li></li>
+<li>Derived classes of RandomVariable (i.e. the random variable 
+implementations) have been ported to a new RandomVariableStream base class.
+<li>For a given distribution DistributionVariable (such as UniformVariable),
+the new class name is DistributionRandomVariable (such as 
+UniformRandomVariable). </li>
+<li>The new implementations are also derived from class ns3::Object and 
+are handled using the ns-3 smart pointer (Ptr) class.  </li>
+<li>The new variable classes also have a new attributed called "Stream"
+which allows them to be assigned to a fix stream index when assigned
+to the underlying pseudo-random stream of numbers.</li>
+</li>
 </ul>
 
 <h2>Changes to build system:</h2>
@@ -63,7 +75,11 @@ <h2>Changes to build system:</h2>
 
 <h2>Changed behavior:</h2>
 <ul>
-<li></li>
+<li>Programs using random variables or models that include random variables 
+may exhibit changed output for a given run number or seed, due to a possible 
+change in the order in which random variables are assigned to underlying 
+pseudo-random sequences.  Consult the manual for more information regarding 
+this.</li>
 </ul>
 
 <hr>

RELEASE_NOTES

@@ -21,9 +21,19 @@ Supported platforms
 
 New user-visible features
 -------------------------
+- A new random variable base class called 'RandomVariableStream', has been
+introduced.  This base class derives from ns3::Object, unlike the current 
+'RandomVariable' class which is a special type of object in the ns-3 
+system to date.  By making this class derive from ns3::Object, it can be 
+handled with the Ptr class, can carry attributes, and can have its parameters
+and initial state saved in the config-store subsystem.  A new attribute
+called "Stream" has been introduced for this class, to allow users to
+better control the assignment of underlying pseudo-random sequences to
+the RandomVariableStream objects (bug 101).
 
 Bugs fixed
 ----------
+ - bug 101 - random variable initialization
 
 Known issues
 ------------