Add guidance on enabling both SSO and email authentication

[inkeep-content-writer]

Summary

This PR adds documentation clarifying how to enable both SSO and email authentication for customers in Kinde.

Changes Made

Updated src/content/docs/authenticate/auth-guides/enterprise-connections-identity.mdx to include a new section: "Can I enable both SSO and email authentication?"

Key Points Addressed

1. Users with enterprise identities cannot use email authentication - Enterprise identity users can only have one identity type from their IdP
2. Users with email identities can have multiple non-enterprise types - Email users can combine email, social, and phone authentication
3. How to enable both methods for different users - Step-by-step instructions for configuring both authentication methods at the environment level

Support Conversation Context

This update directly addresses a common support question: "How can I enable for a customer SSO and Email?"

The documentation now clearly explains:

• The constraint that enterprise identity users cannot also use email authentication
• How to enable both authentication methods in an application to support different user types
• Where to find detailed setup instructions

Related Documentation

• Links to Select authentication options
• References existing enterprise connection setup guides