database/sql: form a complete sentence in code comment

Change-Id: Ib6d0f81b5f64473f9ee6be26a08d5102e8edadc4
Reviewed-on: https://go-review.googlesource.com/c/go/+/229477
Reviewed-by: Daniel Theophanes <[email protected]>

Author: kevinburke

src/database/sql/sql.go

@@ -3013,10 +3013,11 @@ func (ci *ColumnType) Nullable() (nullable, ok bool) {
 }
 
 // DatabaseTypeName returns the database system name of the column type. If an empty
-// string is returned the driver type name is not supported.
+// string is returned, then the driver type name is not supported.
 // Consult your driver documentation for a list of driver data types. Length specifiers
 // are not included.
-// Common type include "VARCHAR", "TEXT", "NVARCHAR", "DECIMAL", "BOOL", "INT", "BIGINT".
+// Common type names include "VARCHAR", "TEXT", "NVARCHAR", "DECIMAL", "BOOL",
+// "INT", and "BIGINT".
 func (ci *ColumnType) DatabaseTypeName() string {
 	return ci.databaseType
 }