Change 'exhibition' to 'display' in subheadings based on exhibition type

[LaurenFBaily]

What

Change word 'exhibition' to 'display' in hard-coded subheaders for upcoming gallery 3 exhibitions (dynamically based on exhibition format = 'display'?). Optional page sections with headings are:

• [Exhibition] highlights
• In this [exhibition]
• [Exhibition] access content

Why

New series of gallery 3 exhibitions will be referred to as 'displays' in order to manage visitor expectations (in terms of scale) and also avoid parallels being drawn with Medicine Man

Background

Done when

[LaurenFBaily]

Suggestion discussed in Planning - could we use exhibition format for other types of exhibitions eg. installation and season (exception of 'permanent exhibition' which should just be exhibition)

[georgiaewhitney]

I believe the first [Exhibition] highlights is manually set by the EditorialImageGallery slice.