Merge pull request #25 from apache/PengZheng-patch-1

Update volunteers.md
diff --git a/source/contributing/volunteers.md b/source/contributing/volunteers.md
index 185618e..a454bae 100644
--- a/source/contributing/volunteers.md
+++ b/source/contributing/volunteers.md
@@ -22,6 +22,7 @@
 - Gabriele Ricciardi (gricciardi at apache.org)
 - Roy Lenferink (rlenferink at apache.org)
 - Erjan Altena (erjanaltena at apache.org)
+- Peng Zheng (pengzheng at apache.org)
 
 ## Committers
 
@@ -33,4 +34,6 @@
 - Roy Bulter (rbulter at apache.org)
 - Idzard Hoekstra (idzardh at apache.org)
 - Michael de Lang (oipo at apache.org)
-- Peng Zheng (pengzheng at apache.org)
+- Rick Stegeman (stegemr at apache.org)
+- Zhenbao Xu (xuzhenbao at apache.org)
+