Incorrect Example for Defining Composite Primary Keys

The current documentation on the Drizzle ORM website provides an incorrect example for defining composite primary keys for `postgreSQL` using the primaryKey operator. Specifically, the example adds the primaryKey definitions inside an object with keys pk and pkWithCustomName, which does not align with the correct syntax.

### Current Example:
```js
export const booksToAuthors = pgTable("books_to_authors", {
authorId: integer("author_id"),
bookId: integer("book_id"),
}, (table) => {
return [{
pk: primaryKey({ columns: [table.bookId, table.authorId] }),
pkWithCustomName: primaryKey({ name: 'custom_name', columns: [table.bookId, table.authorId] }),
}];
});
```

### Expected Example (Correct):
```js
export const booksToAuthors = pgTable(
"books_to_authors",
{
authorId: integer("author_id"),
bookId: integer("book_id"),
},
(table) => {
return [
primaryKey({ columns: [table.bookId, table.authorId] }),
primaryKey({ name: "custom_name", columns: [table.bookId, table.authorId] }),
];
},
);
```

The current example may mislead developers into defining composite primary keys incorrectly, resulting in potential runtime errors or unexpected behavior when working with Drizzle ORM.