npm: improve tldraw package readme (#3851)

If you get to tldraw via the npm search results, you get to a readme
that is very ...odd, or at least uninviting. It tells you this is the
source code (hah, ok? :P) and tells you to run the local development
server to get started. Nope! We should be clearer here.

Screenshot:
<img width="926" alt="Screenshot 2024-05-30 at 14 11 33"
src="https://github.com/tldraw/tldraw/assets/469604/64fcce89-981b-4ae7-8b85-2762820888df">


### Change Type

<!-- ❗ Please select a 'Scope' label ❗️ -->

- [ ] `sdk` — Changes the tldraw SDK
- [ ] `dotcom` — Changes the tldraw.com web app
- [ ] `docs` — Changes to the documentation, examples, or templates.
- [ ] `vs code` — Changes to the vscode plugin
- [x] `internal` — Does not affect user-facing stuff

<!-- ❗ Please select a 'Type' label ❗️ -->

- [ ] `bugfix` — Bug fix
- [ ] `feature` — New feature
- [ ] `improvement` — Improving existing features
- [ ] `chore` — Updating dependencies, other boring stuff
- [ ] `galaxy brain` — Architectural changes
- [ ] `tests` — Changes to any test code
- [ ] `tools` — Changes to infrastructure, CI, internal scripts,
debugging tools, etc.
- [x] `dunno` — I don't know

packages/tldraw/README.md

@@ -7,7 +7,13 @@
 
 # tldraw
 
-This package contains the source code for the tldraw library. Learn more at our docs site: [tldraw.dev](https://tldraw.dev).
+<div style="margin: -1.5rem 0 1.5rem 0; font-size: 12px;">a very good whiteboard</div>
+
+You can use the tldraw SDK to craft infinite canvas experiences for the web. It's perfect for collaborative whiteboards but you can use it for lots of other things, too.
+
+Learn more at our docs site: [tldraw.dev](https://tldraw.dev).
+
+This package is the main entry point when using tldraw. It's part of a larger suite of packages that you can find [here](https://www.npmjs.com/search?q=%40tldraw).
 
 ## Installation
 
@@ -17,12 +23,6 @@ Install the `tldraw` package.
 npm i tldraw
 ```
 
-Then start the local development server.
-
-```bash
-npm run dev
-```
-
 ## Usage
 
 ```tsx
@@ -36,6 +36,14 @@ export default function () {
 
 Visit or [docs site](https://tldraw.dev) to learn more. See our [examples folder](https://github.com/tldraw/tldraw/tree/main/apps/examples) for more examples.
 
+## Package development
+
+To start the local development server:
+
+```bash
+npm run dev
+```
+
 ## Community
 
 Have questions, comments or feedback? [Join our discord](https://discord.gg/rhsyWMUJxd) or [start a discussion](https://github.com/tldraw/tldraw/discussions/new).