Tag Implication: mutual_yuri -> yuri

Implicating mutual_yuri -> yuri.

Reason: Surprised this wasn't done yet.

I suggested it in forum #50492, but it wasn't possible back then. (since it was a pool)

This was one of the requests of the opening of forum #68156.

Danielx21 said:
Pool to tag: pool #1885 -> mutual_yuri
Implication: mutual_yuri -> yuri
Alias: yuri_couple -> mutual_yuri

Reason: The pool is just a yuri version of couple. It's a straightforward, simple, objective concept.

(Note: Don't forget to leave the abandoned pool with a link to the tag, in case the deletion takes place.)

@Danielx21 The pool was never just a yuri version of couple tag. There are yuri couple images that do not match the criteria for the former-pool-now-tag. Not all mutual yuri images qualify for the couple tag either.

Done.