docs: consolidate getting started and context

[wkillerud]

Rework the intro somewhat and move getting started content to its own section.

Probably better to checkout the branch locally and run the server

git checkout podium-store-bridge-browser
npm install && npm start

[wkillerud]

Couldn't help myself now that I need to add some content for new modules 🙈

[leftieFriele]

Awesome work 💯 I left some suggestions which I feel improved things, but you're free to ignore them if you don't agree 😄

Making this structural change should make getting introduced to Podium easier 💪

[leftieFriele]

I really like this removal of "very simple" and things like that. if we want to let the reader know something isn't "how you would do it in production", we should say that 👍

[wkillerud]

Redirects tested OK with npm run build && npm run serve.