How to name a Dexterity field index in portal_catalog?

I have a Dexterity content type named Policy. Within Policy, I have created a field called policy_manual_effective_date. I have added this field into the Table Columns for the Collection content type by adding policy_manual_effective date into the portal_catalog index and metadata

I can now choose this field to appear in a collections table view without any issues. However, the problem now is that the column header says, "policy_manual_effective_date". What I would like it to show is a proper title name, "Policy Manual Effective Date".

Where and what should I do to give the field index a proper title name? I would eventually like to add this to my Dexterity product. Any advise would be most appreciated. Thank you.

Which version of Plone you are using?

Plone 5.0.7 (5017)
CMF 2.2.10
Zope 2.13.26
Python 2.7.12 (default, Nov 19 2016, 06:48:10) [GCC 5.4.0 20160609]
PIL 3.4.2 (Pillow)