Use ?NNN format instead of ?

https://sqlite.org/lang_expr.html#parameters
> But because it is easy to miscount the question marks, the use of this parameter format is discouraged. Programmers are encouraged to use one of the symbolic formats below or the ?NNN format above instead.

src/blob/mod.rs

@@ -134,7 +134,7 @@
 //! // Insert another BLOB, this time using a parameter passed in from
 //! // rust (potentially with a dynamic size).
 //! db.execute(
-//!     "INSERT INTO test_table (content) VALUES (?)",
+//!     "INSERT INTO test_table (content) VALUES (?1)",
 //!     [ZeroBlob(64)],
 //! )?;
 //!
@@ -175,7 +175,7 @@
 //! // Insert another blob, this time using a parameter passed in from
 //! // rust (potentially with a dynamic size).
 //! db.execute(
-//!     "INSERT INTO test_table (content) VALUES (?)",
+//!     "INSERT INTO test_table (content) VALUES (?1)",
 //!     [ZeroBlob(64)],
 //! )?;
 //!