Update wiki pages.

wiki/Statements.md

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+
+Following statements are supported: 
+
+* [SELECT](https://github.com/go-jet/jet/wiki/SELECT)
+* [INSERT](https://github.com/go-jet/jet/wiki/INSERT)
+* [UPDATE](https://github.com/go-jet/jet/wiki/UPDATE)
+* [DELETE](https://github.com/go-jet/jet/wiki/DELETE)
+* [LOCK](https://github.com/go-jet/jet/wiki/LOCK)
+
+_This list might be extended with feature Jet releases._ 
+
+There is a common set of action that can be performed for each statement type:
+
+- `Sql() (query string, args []interface{}, err error)` - retrieves parametrized sql query with list of arguments
+- `DebugSql() (query string, err error)` - retrieves debug query where every parametrized placeholder is replaced with its argument.
+- `Query(db execution.DB, destination interface{}) error` - executes statements over database connection db and stores row result in destination.
+- `QueryContext(db execution.DB, context context.Context, destination interface{}) error` - executes statement with a context over database connection db and stores row result in destination.
+- `Exec(db execution.DB) (sql.Result, error)` - executes statement over db connection without returning any rows.
+- `ExecContext(db execution.DB, context context.Context) (sql.Result, error)` - executes statement with context over db connection without returning any rows.
+
+Database connection can be of any type that implements following interface:
+
+```go
+type DB interface {
+	Exec(query string, args ...interface{}) (sql.Result, error)
+	ExecContext(ctx context.Context, query string, args ...interface{}) (sql.Result, error)
+	Query(query string, args ...interface{}) (*sql.Rows, error)
+	QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error)
+}
+```
+
+These include but are not limited to: 
+- `sql.DB`
+- `sql.Tx`
+- `sql.Conn`