Fix example code for D1 storage

[ss49919201]

Existing documentation URL(s)

• https://developers.cloudflare.com/workers/testing/miniflare/storage/d1/

What changes are you suggesting?

const db = await mf.getD1Database("DB");
const { results } = await db.prepare("<Query>");

The above code in the document is incorrect.
D1Database.prepare returns D1PreparedStatement.
But it looks as if it is returning D1Result.
Should call run or all!

Additional information

No response