Update customize-signup-and-login-prompts.mdx

[BcnCarlos]

Description

References

Testing

Checklist

• I've read and followed CONTRIBUTING.md.
• I've tested the site build for this change locally.
• I've made appropriate docs updates for any code or config changes.
• I've coordinated with the Product Docs and/or Docs Management team about non-trivial changes.

[github-actions]

Summary

Status	Count
🔍 Total	13
✅ Successful	6
⏳ Timeouts	0
🔀 Redirected	0
👻 Excluded	7
❓ Unknown	0
🚫 Errors	0
⛔ Unsupported	0
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