docs: add RustFS configuration documentation for S3 storage

[majinghe]

Description

RustFS is a S3-compatible object storage, and adding RustFS as a documented S3-compatible storage option for Dify self-hosted deployments.

Changes

1. S3_ENDPOINT description: Added RustFS alongside MinIO as an example of S3-compatible service
2. Configuration tip: Added a dedicated tip section with RustFS-specific configuration details

RustFS Configuration Details

The documentation includes important notes for RustFS users:

• S3 API Port: RustFS uses port 9000 for S3 API (not port 9001 which is the web console)
• Address Style: Must set S3_ADDRESS_STYLE=path for proper bucket addressing
• Complete Example: Provided a full configuration example

Configuration Example

STORAGE_TYPE=s3
S3_ENDPOINT=http://your-rustfs-server:9000
S3_REGION=us-east-1
S3_BUCKET_NAME=dify
S3_ACCESS_KEY=your-access-key
S3_SECRET_KEY=your-secret-key
S3_ADDRESS_STYLE=path

[Copilot]

Pull request overview

Documents RustFS as an S3-compatible storage option for Dify self-hosted deployments by updating the S3 environment variable reference and adding RustFS-specific configuration guidance.

Changes:

• Updated S3_ENDPOINT description to include RustFS as an example of an S3-compatible service.
• Added a RustFS-specific <Tip> under the S3 storage accordion with port/addressing-style guidance and a full .env example.

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[RiskeyL]

@majinghe Thanks for the contribution.

The environment variable reference documents Dify's own configuration surface, and we keep vendor-specific setup guidance out of it. The generic S3 variables (S3_ENDPOINT, S3_ADDRESS_STYLE) already apply to any S3-compatible service, and details like which port serves the S3 API belong in the vendor's own documentation.

If RustFS publishes a "use with Dify" guide on its side, the generic variables documented here should be everything it needs. Closing this PR, and thanks again for taking the time.