[Website] Developer Get started

[oliviaflory]

Update content for Website v2

Developing/Get started

• [x] Remove all mentions of pure React package
• [x] Replace with React wrapper package?
• [ ] Is Summit content outdated at this point?
• [ ] Consider referencing how Carbon intros their Getting started page

[kennylam]

React references removed in https://github.com/carbon-design-system/carbon-for-ibm-dotcom-website/pull/1696