Updated docs and fly.toml file to deploy to fly.io

[manavgup]

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• Documentation Update: Use the Docs Template
  Fixes [Docs]: Deploying to Fly.io #21
  Summary of changes made for the PR:

Created a new deployment guide for MCP Gateway on Fly.io at docs/docs/deployment/fly-io.md.

The guide follows the structure and style of the existing IBM Code Engine deployment documentation for consistency.

Added sections covering:

• Overview of Fly.io as a global container platform with built-in TLS and managed Postgres.
• Prerequisites including Fly.io account, Fly CLI, Docker/Podman, .env file, and fly.toml configuration.
• Detailed setup steps with CLI commands for:
• Initializing the Fly project with fly launch.
• Creating persistent volumes for SQLite.
• Creating and attaching Fly Postgres for production use.
• Setting secrets securely using fly secrets set.
• Deploying the app with fly deploy.
• A sample fly.toml configuration file snippet illustrating app settings, environment variables, mounts, and service ports.
• Instructions for generating JWT tokens and accessing the deployed app.
• Documentation of key features such as persistent volumes, secrets injection, TLS support, custom domain setup, and scaling.
• Additional notes referencing Fly.io official documentation for volume limitations and app restart behavior.

This new guide fills the previous documentation gap by providing a clear, comprehensive Fly.io deployment path for MCP Gateway users.

[crivetimihai]

I love this, great PR!