Update models with adaptation mechanisms and change tag 'adaptive threshold' to 'adaptation'

[jessica-mitchell]

This PR updates the model tag for models that use an adaptation mechanism to 'adaptation' after discussions with @ddahmen The reason is that not all the models have the same adaptation mechanism, and the ones labeled with adaptive threshold (i.e. 'aeif' models) technically do not have an adaptive threshold. We were also missing tags for several models that have an adaptation mechanism but were not 'aeif' models.

See Read the Docs output here: https://nest-simulator--3241.org.readthedocs.build/en/3241/models/index.html#adaptation