add the ability to publish observable plots

[llimllib]

Maybe some interface like

```js observable
Plot.plot(
   ...
)
```

Would be a good interface?

• I'd also have to solve the problem of getting data in somehow
• maybe would be better just to point to an observable framework page somewhere else?
• might want to have this as an obsidian extension
  • there's a vega plugin I could crib from