Update 12-keywords.md

docs/en/12-taos-sql/12-keywords.md

@@ -4,7 +4,7 @@ title: Keywords
 
 There are about 200 keywords reserved by TDengine, they can't be used as the name of database, STable or table with either upper case, lower case or mixed case.
 
-**Keywords List**
+## Keyword List
 
 ### A
 
@@ -311,4 +311,4 @@ The start, stop and duration of a query time window (Since version 2.6.0.0).
 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.
+The first column of a table or STable.
\ No newline at end of file