docs: improve documentation on hooks and inflections

[jclusso]

For the life of me, I can't figure out where usage of hooks go when working with them directly. A proper example would be greatly helpful here. If they belong in the initializer or a config. I figured it would be nice to have a hooks.rb file in the config folder, but I was unsuccessful in getting that to work.

bridgetown/bridgetown-website/src/_docs/plugins/hooks.md

Lines 24 to 28 in 6ff7de5

	# or using the hooks API directly:
	Bridgetown::Hooks.register_one :posts, :post_render do |post|
	# code to call after Bridgetown renders a post
	end
	```

This also leads me to having no idea how to get inflections to work. I think a full example showing where and what hook it should use would be great.

bridgetown/bridgetown-website/src/_docs/resources.md

Lines 248 to 255 in 6ff7de5

	The "inflector" loaded in from Rails' ActiveSupport is used to convert between singular and plural collection names automatically. If you need to customize the inflector with words it doesn't specifically recognize, create a plugin and add your own:
	```ruby
	ActiveSuport::Inflector.inflections(:en) do |inflect|
	inflect.plural /^(ox)$/i, '\1\2en'
	inflect.singular /^(ox)en/i, '\1'
	end
	```

[jclusso]

The second part of this can be ignored once #793 is merged.

[jaredcwhite]

@jclusso Thanks for calling this out. Part of the issue I think is I really dislike that hooks API, as it's a holdover from Jekyll days, and I've been trying to move away from it in various ways. I'm realizing now there's not adequate documentation on how to use hook in initializer files, which is the new preferred way to define hooks going forward outside of a Builder. It needs updating here: https://www.bridgetownrb.com/docs/configuration/initializers