fixed #637, 'concurrentcy' typo error (#697)

docs/docs/docs-cn/13.reference-guide/1.system-view/3.performance-view/62.v-sql.md

@@ -41,7 +41,7 @@ gv$sql
 | DIRECT_WRITES         | bigint(20)          | NO             | 写盘次数                                                                                                             |
 | BUFFER_GETS           | bigint(20)          | NO             | 逻辑读次数                                                                                                            |
 | APPLICATION_WAIT_TIME | bigint(20) unsigned | NO             | application 类事件等待时间                                                                                              |
-| CONCURRENCY_WAIT_TIME | bigint(20) unsigned | NO             | concurrentcy 类事件等待时间                                                                                             |
+| CONCURRENCY_WAIT_TIME | bigint(20) unsigned | NO             | concurrency 类事件等待时间                                                                                             |
 | USER_IO_WAIT_TIME     | bigint(20) unsigned | NO             | 所有 IO 类事件等待时间                                                                                                    |
 | ROWS_PROCESSED        | bigint(20)          | NO             | 所有 Schedule 类事件等待事件                                                                                              |
 | ELAPSED_TIME          | bigint(20) unsigned | NO             | 接收到处理完成总消耗时间                                                                                                     |