Allow <random>. Add cautionary note about xxx_distribution.

styleguide/c++/c++11.html

Index: styleguide/c++/c++11.html
diff --git a/styleguide/c++/c++11.html b/styleguide/c++/c++11.html
index dc2728b74df608b413a34e915160c36aa0e166a4..7942890fffd011770c4821b8afc0ab8b9cf9dfae 100644
--- a/styleguide/c++/c++11.html
+++ b/styleguide/c++/c++11.html
@@ -457,6 +457,14 @@ template &lt;typename T&gt;<br/>void Function(T&& t) { ... }</code></td>
 </tr>
 
 <tr>
+<td>Random Number Generators</td>
+<td><code>&lt;random&gt;</code></td>
+<td>Random number generation algorithms and utilities</td>
+<td><a href="http://en.cppreference.com/w/cpp/numeric/random">Pseudo-random number generation</a></td>
+<td>Because the standard does not define precisely how the <code><i>xxx</i>_distribution</code> objects generate output, the same object may produce different output for the same seed across platforms, or even across different versions of the STL. Do not use these objects in any scenario where behavioral consistency is required. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/cxx/MLgK9vCE4BA">Discussion thread</a></td>
+</tr>
+
+<tr>
 <td>String Direct Reference Functions</td>
 <td><code>std::string::front()</code>, <code>std::string::back()</code></td>
 <td>Returns a reference to the front or back of a string</td>
@@ -843,14 +851,6 @@ work in all our compilers yet.</p>
 </tr>
 
 <tr>
-<td>Random Number Generators</td>
-<td>Functions within <code>&lt;random&gt;</code></td>
-<td>Random number generation algorithms and utilities</td>
-<td><a href="http://en.cppreference.com/w/cpp/numeric/random">Pseudo-random number generation</a></td>
-<td></td>
-</tr>
-
-<tr>
 <td>Ratio Template Class</td>
 <td><code>std::ratio&lt;<i>numerator</i>, <i>denominator</i>&gt;</code></td>
 <td>Provides compile-time rational numbers</td>