Topic: category sex_position_request -> meta

The bulk update request #1372 is pending approval.

change category sex_position_request (3) -> meta

Reason: meta seems the best category for this tag

This seems like a disambiguation may be better, or at least a different name. A number of other *_request tags refer to a character requesting something in the image, like impregnation_request, anal_request, sex_request, etc, and sex_position_request at first made me think it was for a character asking to do particular sex positions.