wpdb::prepare PHPDoc recommends bad PHP

[TJNowell]

The phpdoc of the prepare method recommends calling it statically via the examples. Doing this would cause PHP warnings and notices.

I've attached a diff that should correct this by changing wpdb::prepare to $wpdb->prepare

[TJNowell]

A diff to be applied to wp-db.php that adjusts the phpdocs of wpdb::prepare

[pento]

Good catch, thanks @TJNowell!

[SergeyBiryukov]

In 38289:

Docs: Correct usage examples for wpdb::prepare(), which should not be called statically.

Props TJNowell.
Fixes #37744.