docs: document alias_attribute behavior change in Rails 7.2 upgrading guide

Author: shravan097

guides/source/upgrading_ruby_on_rails.md

@@ -104,6 +104,60 @@ set the `queue_adapter` config to something other than `:test`, but written test
 
 If no config is provided, the `TestAdapter` will continue to be used.
 
+### `alias_attribute` now bypasses custom methods on the original attribute
+
+In Rails 7.2, `alias_attribute` now bypasses custom methods defined on the original attribute and directly accesses the underlying database value. This change was announced via deprecation warnings in Rails 7.1.
+
+**Before (Rails 7.1):**
+
+```ruby
+class User < ActiveRecord::Base
+  def email
+    "custom_#{super}"
+  end
+
+  alias_attribute :username, :email
+end
+
+user = User.create!(email: "[email protected]")
+user.username
+# => "[email protected]"
+```
+
+**After (Rails 7.2):**
+
+```ruby
+user = User.create!(email: "[email protected]")
+user.username
+# => "[email protected]"  # Raw database value
+```
+
+If you received the deprecation warning "Since Rails 7.2 `#{method_name}` will not be calling `#{target_name}` anymore", you should manually define the alias method:
+
+```ruby
+class User < ActiveRecord::Base
+  def email
+    "custom_#{super}"
+  end
+
+  def username
+    email  # This will call the custom email method
+  end
+end
+```
+
+Alternatively, you can use `alias_method`:
+
+```ruby
+class User < ActiveRecord::Base
+  def email
+    "custom_#{super}"
+  end
+
+  alias_method :username, :email
+end
+```
+
 Upgrading from Rails 7.0 to Rails 7.1
 -------------------------------------