[👩‍💻 Documentation Request]: SAML SSO IDP configuration example

### Summary

Write page that helps configure SAML SSO IDP

### Why is it needed?

Because it's helps users

### Want to write this documentation yourself?

Yes

### Related PR(s)

https://github.com/scaleway/docs-content/pull/5879

### (Optional) Scaleway Organization ID

6c3da02a-2d3c-4357-aba4-313f811f7c07

### Email address

contact@christianvdz.fr