docs: Add Wikifunctions to community servers list

[Fredibau]

Description

This pull request adds the new "Wikifunctions" server to the list of community servers in the main README.md file, as per the contribution guidelines.

Server Details

• N/A - This change adds a new server to the documentation, it does not modify an existing server's code.

Motivation and Context

The motivation is to make the community aware of the Wikifunctions MCP server, which allows AI models to discover and execute functions from the WikiFunctions library. This adds a valuable new tool to the MCP ecosystem.

How Has This Been Tested?

This is a documentation-only change and does not require testing with an LLM client. The alphabetical ordering of the list has been maintained.

Breaking Changes

None.

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

No additional context.