Add documentation for manage_datadog_error_tracking_issue_links mcp tool

[milanboers]

What does this PR do? What is the motivation?

Documents the manage_datadog_error_tracking_issue_links MCP tool, which moved into the public error-tracking toolset.

• Adds a new entry to the Error Tracking section of the MCP tools reference
  • Describes creating, linking, and unlinking Jira tickets, Linear tickets, and Datadog cases for an Error Tracking Issue
  • Follows the existing format used by sibling Error Tracking tools (toolset, required permissions, description, example prompts)

Merge readiness

• Ready for merge

For Datadog employees:

• ⚠️ Your branch name MUST follow the <name>/<description> convention and include the forward slash (/). If you've already created your PR with an incorrect branch name, please rename your branch and open a fresh PR.
• 🤖 New: Comment with /review to run an automated check that catches common issues before a Documentation team member reviews your PR.

AI assistance

Used Claude Code to draft the new tool documentation entry, based on the tool's source code.

Additional notes

[github-actions]

Preview links (active after the build_preview check completes)

Modified Files

• https://docs-staging.datadoghq.com/milanboers/links-tool-ga/mcp_server/tools