Fix unclosed tag

Author: lkollar

Doc/library/profiling-sampling-visualization.html

@@ -1,3 +1,3 @@
-<link rel="stylesheet" href="../_static/profiling-sampling-visualization.css">
+<link rel="stylesheet" href="../_static/profiling-sampling-visualization.css" />
 <div id="sampling-profiler-viz" class="sampling-profiler-viz"></div>
 <script src="../_static/profiling-sampling-visualization.js"></script>