SSO - add info about SSO to sign up

[alex-cit]

• Available for Cloud and EE / SSO login is available on dashboard, mobile and qgis-plugin
• SAML and OAUTH protocols are available
• How to ask for SSO on Cloud (workspace settings)
• Details in workspace settings when SSO is configured
• How to set up new connection
  • Cloud - ask sales and you'll receive a link with step-by-step guide for your identity provider
  • EE - set it up in admin portal, according to SSO article from Marcel - last step is to create new connection

[tomasMizera]

We should create a dedicated page for SSO - extract some information from "How to sign up" page (like connection setup) and add info that if someone wants to remove user from their IDP, they shall also remove them from their workspace (because the user's session might still be valid!)