[tracking ticket] docs update

[heyjay44]

Ask: docs are half as long

Eric:

• update messaging on welcome page: https://use-fireproof.com/docs/welcome/
  • Consider removing code snippets since that reads like a quickstart
• how do we want the concept guide to fit into the narrative: https://use-fireproof.com/docs/category/concept-guide

Marty:

1. update technical details on:

• P0: quickstart: https://use-fireproof.com/docs/getting-started
• P0: react tutorial: https://use-fireproof.com/docs/react-tutorial
• P1: https://use-fireproof.com/docs/solid-tutorial (or consider removing for now, there is a lot of surface area to the docs)