docs, `ActiveRecord::JoinDependency` is not part of the public API.

[ci skip]

While `JoinDependency` and `JoinDependency::Aliases` were nodoced, the
inner `Table` class made them appear in the API.

activerecord/lib/active_record/associations/join_dependency.rb

@@ -32,7 +32,7 @@ def column_alias(node, column)
           @alias_cache[node][column]
         end
 
-        class Table < Struct.new(:node, :columns)
+        class Table < Struct.new(:node, :columns) # :nodoc:
           def table
             Arel::Nodes::TableAlias.new node.table, node.aliased_table_name
           end