docs: add Logto to SSO, IAM

[Rany0101]

Logto is an open-source Auth0, Cognito and Firebase auth alternative for modern apps and SaaS products, supporting OIDC, OAuth 2.0 and SAML open standards for authentication and authorization.

Repo: https://github.com/logto-io/logto Website: https://logto.io/ Docs: https://docs.logto.io/

[CLAassistant]

All committers have signed the CLA.