Update ONOS readme with YourKit endorsement.

Change-Id: I1cd600462b339e856ca9aada4678397e2600c822
diff --git a/README.md b/README.md
index 3d91143..2da661d 100644
--- a/README.md
+++ b/README.md
@@ -151,3 +151,10 @@
 
 ONOS (Open Network Operating System) is published under [Apache License
 2.0](https://github.com/opennetworkinglab/onos/blob/master/LICENSE.txt)
+
+## Acknowledgements
+YourKit supports open source projects with innovative and intelligent tools
+for monitoring and profiling Java and .NET applications.
+YourKit is the creator of [YourKit Java Profiler](https://www.yourkit.com/java/profiler/), [YourKit .NET Profiler](https://www.yourkit.com/.net/profiler/) and [YourKit YouMonitor](https://www.yourkit.com/youmonitor/).
+
+![YourKit](https://www.yourkit.com/images/yklogo.png)