Add Gerrit-PluginName in BUCK file

Change-Id: I9994a9be37ea4692df24520a00a4ef7755ba9866

BUCK

diff --git a/BUCK b/BUCK
index 21043f8..da5d262 100644
--- a/BUCK
+++ b/BUCK
@@ -3,6 +3,7 @@
   srcs = glob(['src/main/java/**/*.java']),
   resources = glob(['src/main/resources/**/*']),
   manifest_entries = [
+    'Gerrit-PluginName: download-commands',
     'Gerrit-Module: com.googlesource.gerrit.plugins.download.Module'
   ]
 )