Document the differences between Radashi isEmpty and Lodash isEmpty

[aleclarson]

I would appreciate if someone could investigate this. Ideally, our isEmpty would pass all Lodash tests where it makes sense.

• Lodash docs: https://lodash.com/docs/4.17.15#isEmpty

• Lodash tests: https://github.com/lodash/lodash/blob/main/test/isEmpty.spec.js

• Radashi docs: https://github.com/radashi-org/radashi/blob/main/docs/typed/is-empty.mdx

• Radashi tests: https://github.com/radashi-org/radashi/blob/main/tests/typed/isEmpty.test.ts