Create implication pov_across_bed -> on_bed

BUR #10342 has been approved by @nonamethanks.

create implication pov_across_bed -> on_bed

Seems like this tag always applies so might as well imply it.

This bulk update request is pending automatic rejection in 5 days.

This bulk update request has been rejected because it was not approved within 45 days.

The bulk update request #10342 (forum #212685) has been rejected by @DanbooruBot.

The bulk update request #10342 (forum #212685) has been approved by @nonamethanks.