readme: fix formatting error
- No `package.json`. No npm. Not explicitly compatible with Node.
- Imports reference source code URLs only.
- `import { test } from "https://unpkg.com/deno_testing@0.0.5/testing.ts" import { log } from "./util.ts"`
+
+ ```typescript
+ import { test } from "https://unpkg.com/deno_testing@0.0.5/testing.ts";
+ import { log } from "./util.ts";
+ ```
+
Remote code is fetched and cached on first execution, and never updated until
the code is run with the `--reload` flag. (So, this will still work on an
airplane. See `~/.deno/src` for details on the cache.)
