The `standing_sign` special model renderer uses a field misspelled as "attachement"

The StandingSignSpecialRenderer codec uses the misspelled field name "attachement" (extra 'e') instead of "attachment" for the optional attachment type field in item model definitions.

In StandingSignSpecialRenderer.java:

PlainSignBlock.Attachment.CODEC
    .optionalFieldOf("attachement", PlainSignBlock.Attachment.GROUND)

Should be:

PlainSignBlock.Attachment.CODEC
    .optionalFieldOf("attachment", PlainSignBlock.Attachment.GROUND)

The HangingSignSpecialRenderer correctly uses "attachment".

This is the same typo that previously existed in jigsaw block data as "attachement_type", which was fixed via JigsawPropertiesFix.

No vanilla item definitions use the minecraft:standing_sign special model type, so this has gone unnoticed. It would affect any resource pack attempting to use this special type with a non-default attachment.