Docs: Add Differences with orval.dev

[x-N0]

Description

Add differences comparison against orval, since it tries to achieve a similar outcome as this library. I think would be helpful for users deciding between both packages.

It can be added right here.

Proposal

Add an entry into the Differences section comparing with orval.dev package.

Extra

• [x] I’m willing to open a PR (see CONTRIBUTING.md)