Implement the revised onBoarding/Getting Started work

Background:

As part of the eLife work, the 'Getting Started' card was revised to be more clear and user friendly.

It was decided that the 'Getting Started' card should be universally implemented across the client.

However, the design was only implemented for eLife due to time constraints, so the outstanding work is to push out the revised getting started card to all Hypothesis users.

The previous issue which contained both pieces or work has since been closed, so adding the revised 'Getting Started' designs below.

Thanks!

@sheetaluk implemented the eLife 'Getting Started' configuration so please liaise with her as a design pattern exists already for this but what needs to change is the content/text block instructions (Hypothesis has more instructions than eLife) and the colours of the CTA (eLife: blue -> Hypothesis grey).

Revised Getting Started Design:

Existing Getting Started Card:

Start by reviewing the existing eLife Getting Started configuration and the two supplied designs, then liaise with @sheetaluk about the established pattern. Update the card for all Hypothesis users with the Hypothesis-specific instruction text and grey CTA, and verify that the revised card appears consistently across the client.