Apply suggestions from code review

Co-authored-by: Tim Vaillancourt <[email protected]>

Author: wangzihuacool

go/cmd/gh-ost/main.go

@@ -68,7 +68,7 @@ func main() {
 	flag.StringVar(&migrationContext.OriginalTableName, "table", "", "table name (mandatory)")
 	flag.StringVar(&migrationContext.AlterStatement, "alter", "", "alter statement (mandatory)")
 	flag.BoolVar(&migrationContext.AttemptInstantDDL, "attempt-instant-ddl", false, "Attempt to use instant DDL for this migration first")
-	storageEngine := flag.String("storage-engine", "innodb", "Specify table storage engine (default: 'innodb'). When 'rocksdb': change session transaction isolation level to READ_COMMITTED.")
+	storageEngine := flag.String("storage-engine", "innodb", "Specify table storage engine (default: 'innodb'). When 'rocksdb': the session transaction isolation level is changed from REPEATABLE_READ to READ_COMMITTED.")
 
 	flag.BoolVar(&migrationContext.CountTableRows, "exact-rowcount", false, "actually count table rows as opposed to estimate them (results in more accurate progress estimation)")
 	flag.BoolVar(&migrationContext.ConcurrentCountTableRows, "concurrent-rowcount", true, "(with --exact-rowcount), when true (default): count rows after row-copy begins, concurrently, and adjust row estimate later on; when false: first count rows, then start row copy")