[Domains] Review documentcloud.org title option

[siniakinaa]

Scope

Category: Domains

About the changes

• Bug fix (non-breaking change which fixes an issue)
• Changes to existing functionality (improvements or deprecations)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Tests and chores (up)

What has changed

Please describe what the code is doing (in this repo):

• User can disable default title by iframely option