Pool to tag: Perpendicular Paizuri

pool #4848 - Perpendicular Paizuri seems like it would be better suited to a tag, perpendicular_paizuri, than a pool.

This has been brought up in the Pointless Pools thread several times, but I thought a new thread would be good since it didn't go anywhere.

If the tag is made, it would also need an implication perpendicular_paizuri -> paizuri

Thoughts?

the concept is very straightforward and can easily be converted to a tag.

Moved it to a tag.