Add API doc note about statement finalization (WiseLibs#1310)

* Add note about statement finalization

* PR comment

Author: kjackson1998

docs/api.md

@@ -421,6 +421,8 @@ An object representing a single SQL statement.
 - [Statement#bind()](#bindbindparameters---this)
 - [Properties](#properties-1)
 
+> NOTE: Statements are [finalized](https://www.sqlite.org/c3ref/finalize.html) when garbage collected so there is no explicit API for it. Statements are also finalized when the associated database is closed.
+
 ### .run([*...bindParameters*]) -> *object*
 
 Executes the prepared statement. When execution completes it returns an `info` object describing any changes made. The `info` object has two properties: