Update Alternative formats prototype following PEN findings

[martinwake]

What

Update the Alternative formats example prototype to reflect findings from research by the PEN team.

Why

There are several insights that we should adopt into our example service.

Done when

• [x] Remove separate large print option and consolidate into second option
• [x] Rewrite Textphone label and hint text
• [x] Update Check answers headings from "when" to "how"

Details are on "Proposed changes" page in Confluence documentation

Outcomes

Prototype is updated

Who needs to know about this

Design System team PEN team

[jonhurrell]

@martinwake https://dwp-design-system-examples-c0557c2c3d1d.herokuapp.com/examples/alternative-formats/v2/journey-1/index

[jonhurrell]

@martinwake to contact PEN team with changes and diversions.