docs/quickstart is now outdated as `results` and `error` must not be nullable

[TimDaub]

• breaking change: https://github.com/neume-network/schema/blob/main/changelog.md#070
• https://github.com/neume-network/strategies/blob/main/docs/quickstart.md
• I think one problem with having such docs is that (1) they get outdated but (2) we don't notice that they get outdated.
• potentially we wanna consider testing documentation snippets similar to how we're doing it with https://github.com/rugpullindex/eth-fun/blob/master/API.md