[FEATURE REQUEST] Allow "Include" plugin as a top-level key

First, sorry to put this as uncategorized, it won’t let me create a topic in the “Feature Request” category.

With that out of the way, Id like to propose using the include plugin as a top-level key.

I think this will help with complex configuration by allowing people to split templates up into different files. For example:

include:
  - input_rss_templates.yaml
  - filter_templates.yaml
  - output_templates.yaml
....

Then each file has a top level template key and whatever templates the user desires. Of course I assume this would also work with tasks and other top-level keys as well.