docs: refine keywords in 3.0

docs-cn/12-taos-sql/12-keywords/index.md

@@ -86,7 +86,7 @@ title: TDengine 参数限制与保留关键字
 | CONNS       | ID         | NOTNULL   | STABLE     | WAL          |
 | COPY        | IF         | NOW       | STABLES    | WHERE        |
 | _C0         | _QSTART    | _QSTOP    | _QDURATION | _WSTART      |
-| _WSTOP      | _WDURATION |
+| _WSTOP      | _WDURATION | _ROWTS    |
 
 ## 特殊说明
 ### TBNAME
@@ -124,5 +124,5 @@ Query OK, 1 row(s) in set (0.001091s)
 ### _WSTART/_WSTOP/_WDURATION
 窗口切分聚合查询（例如 interval/session window/state window）中表示每个切分窗口的起始，结束以及持续时间（从 2.6.0.0 版本开始支持）
 
-### _c0
-表示表或超级表的第一列
+### _c0/_ROWTS
+_c0 _ROWTS 等价，表示表或超级表的第一列
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docs-en/12-taos-sql/12-keywords.md

@@ -47,11 +47,11 @@ There are about 200 keywords reserved by TDengine, they can't be used as the nam
 | CONNS       | ID         | NOTNULL   | STable     | WAL          |
 | COPY        | IF         | NOW       | STableS    | WHERE        |
 | _C0         | _QSTART    | _QSTOP    | _QDURATION | _WSTART      |
-| _WSTOP      | _WDURATION |
+| _WSTOP      | _WDURATION | _ROWTS    |
 
 ## Explanations
 ### TBNAME
-`TBNAME` can be considered as a special tag, which represents the name of the subtable, in STable.
+`TBNAME` can be considered as a special tag, which represents the name of the subtable, in a STable.
 
 Get the table name and tag values of all subtables in a STable.
 ```mysql
@@ -85,5 +85,5 @@ The start, stop and duration of a query time window (Since version 2.6.0.0).
 ### _WSTART/_WSTOP/_WDURATION
 The start, stop and duration of aggegate query by time window, like interval, session window, state window (Since version 2.6.0.0).
 
-### _c0
-The first column of a table or STable.
+### _c0/_ROWTS
+_c0 is equal to _ROWTS, it means the first column of a table or STable.
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