docs(connector-smtp): add Gmail SMTP configuration guide and troubleshooting

[Fatty911]

Added specific configuration details for Gmail to prevent common HELO/EHLO errors and SSL/TLS port mismatches.

Summary

This PR updates the connector-smtp README to include specific configuration guidelines for Gmail users.

Testing

I recently set up Logto with Lobe-Chat using Gmail and encountered two critical issues that blocked the process:

1. HELO/EHLO Error: Using non-ASCII characters (e.g., Chinese) in "Sender Name" causes Gmail to reject the connection immediately (501-5.5.4 HELO/EHLO argument invalid).
2. SSL/TLS Mismatch: Configuring Port 587 with Secure: true causes an OpenSSL version number error, which is confusing for users.

Adding this guide will save future users significant debugging time.

Checklist

• .changeset
• unit tests
• integration tests
• necessary TSDoc comments

[github-actions]

COMPARE TO master

Total Size Diff 📈 +988 Bytes

Diff by File

Name	Diff
packages/connectors/connector-smtp/README.md	📈 +988 Bytes