New `acts_as_taggable_on:sharded_db:install_initializer` task is broken

[Mr0grog]

I was upgrading to v10, and tried running the new acts_as_taggable_on:sharded_db:install_initializer Rake task, but I get the following error:

Don't know how to build task 'config/initializers/foo' (See the list of available tasks with `rails --tasks`)
Did you mean?  config/initializers

Tasks: TOP => acts_as_taggable_on:sharded_db:install_initializer

I think this is pretty simple; the task just depends on the wrong prequisite and it should be "config/initializers" (see the directory task below the install_initializer task): https://github.com/mbleigh/acts-as-taggable-on/blob/4acc154dcce00df211dd0d1d43812feaed557de0/lib/tasks/install_initializer.rake#L5-L20

I’m happy to write a PR to fix this! BUT, I was also curious about:

1. base_class is missing from the “configuration” section of the README. Should I add it there?

2. There are no docs for this Rake task; I only found it by reading the release notes. Should I add it to the README somewhere?

3. The current template for the initializer uses the pattern:

   ActsAsTaggableOn.setup do |config|
     config.<whatever> = <value>
   end

   But the docs use the pattern:

   ActsAsTaggableOn.<whatever> = <value>

   Both work fine, but it’s probably good to be consistent. Should one or the other change?

4. The task is namespaced under sharded_db, but it’s mostly just plopping in a generic initializer. Would it be better to rename it to acts_as_taggable_on:install_initializer and add the other config attributes to it?