Fix yAxis label of gc-time panel

Change-Id: Ib330398a5a9034ed34a07df50930aab2202b27d5
diff --git a/dashboards/gerrit/process/panels/gc-time.libsonnet b/dashboards/gerrit/process/panels/gc-time.libsonnet
index 94e46b8..e518e3c 100644
--- a/dashboards/gerrit/process/panels/gc-time.libsonnet
+++ b/dashboards/gerrit/process/panels/gc-time.libsonnet
@@ -7,7 +7,7 @@
 barGraph.new(
   title='Java - % of time spent in GC',
   yAxis1=yAxis.new(
-    label='Open File Descriptors',
+    label='% of time spent in GC',
     format='percentunit',
   ),
 )