[docs] Fix documentation to be clearer for first-time users

[jessmartin]

@nickbasile shared some excellent feedback on the docs after trying to build a Todo list application. His repo is here.

• [x] The React Tutorial that created a counter was a bit confusing due to the simple nature of the counter. Would have preferred a more realistic / complex app.
• [x] The code example for Setting Values in Untyped Mutations are incorrect. It's missing key fields, which tripped up Nick until he added them.
• [ ] "Queries" and "Mutations" was not what he expected when searching the docs for how to update state. He expected something like "CRUD" or "how to read and write data."
• [ ] He would have liked to see a concept overview that was a little higher-level than the React or TypeScript Guide.

Here's the loom where he talked about his confusions.

Other first-time user feedback

• [x] ensure that it is clear that React is an optional dependency (initially reported in https://github.com/dxos/dxos/issues/5521)

[curtcox]

@wittjosiah Thanks for the clarification. The more you attract developers like me who aren't steeped in web development the more you will face issues like this. Hopefully you see it as a badge of success. I thought React and Typescript were independent things since one is a framework and the other is a language.