fix variant function link

Author: BohuTANG

docs/doc/13-sql-reference/10-data-types/30-data-type-string-types.md

@@ -7,9 +7,9 @@ description: Basic String data type.
 
 In Databend, strings can be stored in the VARCHAR field, the storage size is variable.
 
-| Name     | Aliases     | Storage Size
-| -------- | ------------|---------------
-| VARCHAR  | STRING      |  variable
+| Name    | Aliases | Storage Size |
+|---------|---------|--------------|
+| VARCHAR | STRING  | variable     |
 
 ## Functions
 

docs/doc/13-sql-reference/10-data-types/43-data-type-variant.md

@@ -224,4 +224,4 @@ SELECT sum(arr[0]::INT) FROM array_table GROUP BY arr[0]::INT;
 
 ## Functions
 
-See [Variant Functions](/doc/reference/functions/semi-structured-functions).
+See [Variant Functions](/doc/reference/functions/variant-functions).