Added TigerGraph to community server list

[custom-discoveries]

Description

Updated README.md file to add TigerGraph to the community server list

Server Details

• Server:
• Changes to:
  N/A

Motivation and Context

It provides a link to Custom Discoveries TigerGraph MCP Server

How Has This Been Tested?

By viewing the README.md file

Breaking Changes

No

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Protocol Documentation
• My changes follows MCP security best practices
• I have updated the server's README accordingly
• I have tested this with an LLM client
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have documented all environment variables and configuration options

Additional context

[custom-discoveries]

Resolved the (2) conflicts