tag alias: phone_booth -> telephone_booth

Both tags have so few posts that re-tagging can be done instantly but I think we should set up the alias for future posts.

Though phone_booth is the most common name, and has the most posts of the too, I think telephone_booth is the preferable tag title.

The existing tags almost exclusively use the "phone" form, except for telephone_pole. This should be phone_booth for consistency.

Aliased to phone_booth