Add guide for setting up Auth with open source ORY Kratos

I used the React Navigation guide on auth quite extensively when writing the reference for writing how to wire the open source ORY Kratos project into React Native, the result of which can be found at https://github.com/ory/kratos-selfservice-ui-react-native.

I was wondering if it would be of interest/worth to add a section to the auth documentation covering a setup with ORY Kratos and React Native, given that both projects are open source, have a broad community, and are well maintained. I think it could help developers getting into React Native Navigation / React Native solve auth easier and with less frustration and by using Apache 2.0 licensed open source only.

I'd also be happy to check into other projects such as KeyCloak to provide a guide, however the OAuth2 set up makes this much more difficult to nail down in a couple of sections - so this could probably take a bit of time.

从 reactnavigation.org/docs/auth-flow 的 auth-flow 文档开始，并查看链接的 ORY Kratos React Native 参考项目。检查 ORY Kratos 部分是否适合现有的指南结构，并根据所引用的项目核实设置细节。当文档提供一份清晰、准确的 ORY Kratos 接入 React Native 指南时，即视为完成。