Correct CVS -> CSV typo (facebook#8513)

Summary: Pull Request resolved: facebook#8513

Reviewed By: jay-zhuang

Differential Revision: D29654066

Pulled By: mrambacher

fbshipit-source-id: b8f492fe21edd37fe1f1c5a4a0e9153f58bbf3e2

tools/db_bench_tool.cc

@@ -1060,7 +1060,7 @@ DEFINE_int32(stats_per_interval, 0, "Reports additional stats per interval when"
              " this is greater than 0.");
 
 DEFINE_int64(report_interval_seconds, 0,
-             "If greater than zero, it will write simple stats in CVS format "
+             "If greater than zero, it will write simple stats in CSV format "
              "to --report_file every N seconds");
 
 DEFINE_string(report_file, "report.csv",