chore: run pnpm run build before typedoc to avoid type errors (#266)

I noticed earlier today that running `pnpm run docs` fails with a bunch
of typescript errors unless you run `pnpm run build` first.

This just updates the `docs` npm script to `pnpm run build && typedoc
--out docs`, so we'll always have build output to make typedoc happy.

package.json

@@ -13,7 +13,7 @@
  "test": "pnpm -r --if-present run test",
  "check": "pnpm -r --if-present run check",
  "build": "pnpm -r --if-present run build",
- "docs": "typedoc --out docs"
+ "docs": "pnpm run build && typedoc --out docs"
  },
  "devDependencies": {
  "lint-staged": "^13.0.4",