Update social contact info input field labels

[douglas-johnson]

Background

These fields include URL in their labels, but they are not actually forced to be valid URLs. So far it has been up to a theme to decide how to output the social data. In most case we have written something to either, output the URL as stored if its valid and includes the social platform's domain or treat it like a username and apply a URL pattern to it.

Details

• Remove URL from the label property of the items in the $contact_info_fields variable linked above.
• If possible, add help text to the entire contact info meta box to indicate that social link fields can include either a username / handle or a URL.