Add links for GDAL MCP and STAC MCP servers

[JordanGunn]

Description

Adds two geospatial community MCP server links:

• gdal-mcp – Python geospatial workflows (Rasterio, GeoPandas, PyProj) for catalog discovery, metadata intelligence, and raster/vector processing.
• stac-mcp – STAC catalog & item search for rapid geospatial data discovery.

Both entries inserted alphabetically (GDAL after Gcore, STAC after SQL Server). Let me know if you’d prefer different phrasing or categorization.

Motivation and Context

Extends the support for agentic tooling within the geospatial community with two de-facto tools within the respective domain.

How Has This Been Tested?

Two primary methods of testing were utilized:

1. Unit tests for tools, resources, and prompts.
2. E2E testing via standardized prompts providing full capability coverage.

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

[olaservo]

Thanks for your contribution to the servers list. This has been merged in this combined PR: #2973