fix: correct join operator

docs/en/12-taos-sql/30-join.md

@@ -191,11 +191,11 @@ Left/Right ASOF Join are supported between super tables, normal tables, child ta
 
   |    **Operator**   |       **Meaning for Left ASOF Join**       |
   | :-------------: | ------------------------ |
-  | >    | Match rows in the right table whose primary key timestamp is less than and the most closed to the left table's primary key timestamp      |
+  | >    | Match rows in the right table whose primary key timestamp is less than and the most closed to the left table's primary key timestamp      |
-  | >=    | Match rows in the right table whose primary key timestamp is less than or equal to and the most closed to the left table's primary key timestamp  |
+  | >=    | Match rows in the right table whose primary key timestamp is less than or equal to and the most closed to the left table's primary key timestamp  |
   | =    | Match rows in the right table whose primary key timestamp is equal to the left table's primary key timestamp  |
-  | <    | Match rows in the right table whose the primary key timestamp is greater than and the most closed to the left table's primary key timestamp  |
+  | &lt;    | Match rows in the right table whose the primary key timestamp is greater than and the most closed to the left table's primary key timestamp  |
-  | <=    | Match rows in the right table whose primary key timestamp is greater than or equal to and the most closed to the left table's primary key timestamp  |
+  | &lt;=    | Match rows in the right table whose primary key timestamp is greater than or equal to and the most closed to the left table's primary key timestamp  |
 
   For Right ASOF Join, the above operators have the opposite meaning.
 

docs/zh/12-taos-sql/30-join.md

@@ -185,11 +185,11 @@ SELECT ... FROM table_name1 LEFT|RIGHT ASOF JOIN table_name2 [ON ...] [JLIMIT jl
 
   |    **运算符**   |       **Left ASOF 时含义**       |
   | :-------------: | ------------------------ |
-  | >    | 匹配右表中主键时间戳小于左表主键时间戳且时间戳最接近的数据行      |
+  | >    | 匹配右表中主键时间戳小于左表主键时间戳且时间戳最接近的数据行      |
-  | >=    | 匹配右表中主键时间戳小于等于左表主键时间戳且时间戳最接近的数据行  |
+  | >=    | 匹配右表中主键时间戳小于等于左表主键时间戳且时间戳最接近的数据行  |
   | =    | 匹配右表中主键时间戳等于左表主键时间戳的行  |
-  | <    | 匹配右表中主键时间戳大于左表主键时间戳且时间戳最接近的数据行  |
+  | &lt;    | 匹配右表中主键时间戳大于左表主键时间戳且时间戳最接近的数据行  |
-  | <=    | 匹配右表中主键时间戳大于等于左表主键时间戳且时间戳最接近的数据行  |
+  | &lt;=    | 匹配右表中主键时间戳大于等于左表主键时间戳且时间戳最接近的数据行  |
 
   对于 Right ASOF 来说，上述运算符含义正好相反。