Unexpected behavior of `index!` with STI

[matteodepalo]

Description

Calling index! in a model that uses STI creates a separate index with that model's name as its name.

Steps to reproduce

My current setup has a parent model with a few sub-classes:

class Content < ActiveRecord::Base
   include AlgoliaSearch
   
   algoliasearch { ... }
end

class Post < Content
end

When calling Content.find(id).index! or Post.find(id).index! the current implementation creates a new index named Post instead of reusing the parent index Content. I've fixed this by specifying the index name:

class Content < ActiveRecord::Base
   include AlgoliaSearch
   
   algoliasearch index_name: "Content" { ... }
end

I'm also aware I can do Content.where(id: id).reindex! and this will work.

If this is expected behavior then would it be worth mentioning it in the docs?