Remove warnings in configuration files

From Hugo doc:

With v0.109.0 and earlier the basename of the site configuration file was

config instead of hugo. You can use either, but should transition to the new
naming convention when practical.

Therefore config.toml is moved to hugo.toml.

The taxonomyTerm page kind was effectively aliased to the taxonomy page kind

in v0.73.0 (https://github.com/bep/hugo/commit/114d4012a89ca88583de5979a6ec4a4799c739b7)

list and single are unknown configurations. Remove them.

Differential Revision: https://reviews.freebsd.org/D43406