Define reference to an Active Record that has a custom table defined

Here is a #Rails pro tip I discovered while trying to write a migration for defining a belong_to association to a model that had a custom table instead of relying on the Rails convention:

The solution I found was to use an option called to_table defined on the foreign_key attribute of TableDefinition#references

Documentation about this can be found at: 

• Rails Guides - Active Record Migrations\#foreign_keys
• Rails Guides - Association Basics\#self-joins
• Rails API - SchemaStatements\#add_reference