Fix Lucene config option in Doc

Rename from enableIOThrottle to enableAutoIOThrottle

Change-Id: I03329a833729b50281b8e8810e80839fefa37710
diff --git a/Documentation/config-gerrit.txt b/Documentation/config-gerrit.txt
index e8d504a..5d4246b 100644
--- a/Documentation/config-gerrit.txt
+++ b/Documentation/config-gerrit.txt
@@ -2661,7 +2661,7 @@
   maxBufferedDocs = 500
   maxThreadCount = 10
   maxMergeCount = 100
-  enableIOThrottle = false
+  enableAutoIOThrottle = false
 
 ----