Changes to people/ARGOpedia layout

[almontg]

Creating this issue to account for the changes to the old "people" layout that will need to be made to convert it into ARGOpedia; @hkemp2128 please comment and add things here as more things occur to us while experimenting with bringing in the historic event content

changes to frontmatter fields:

• remove "bio_dates," which is currently unused; we may want to move this information into the body of the text or the title as it is important information for users
• change "credit" to "author", as we do in stories, and remove "biography written by"
• retroactively add publish_date for people entries; historical event entries already have this
• add "related maps"

changes to layout:

• consistent display of metadata between stories and ARGOpedia types