[Feature] Readmore component needs refining

[KatiePUX]

Is your feature request related to a problem? Please describe.
Styling update to the read more component:

The as is in build: arrow does not align with the 'read more' content

There is also no hover state (see designs)

For more information, it follows a very similar use case the the GOV 'details' component
https://design-system.service.gov.uk/components/details/

Figma original designs - active/focus state has been refined since these designs were produce so please ignore this active/focus state.