Add docs for the agent handler connector

[gilfeig]

Note

Adds documentation for MergeAgentHandlerTool and links it from the integrations navigation and overview.

• Docs:
  • Add docs/en/tools/integration/mergeagenthandlertool.mdx documenting MergeAgentHandlerTool (installation, requirements, usage examples, advanced workflows, environment vars, error handling, supported integrations).
• Navigation:
  • Update docs/docs.json to include en/tools/integration/mergeagenthandlertool under Integrations.
  • Update en/tools/integration/overview.mdx to include a new entry for Merge Agent Handler Tool.

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[lorenzejay]

@gilfeig Can you add the doc reference here so we see it on the left side tab, then you're all good. https://github.com/crewAIInc/crewAI/blob/main/docs/docs.json#L146

[gilfeig]

@gilfeig Can you add the doc reference here so we see it on the left side tab, then you're all good. https://github.com/crewAIInc/crewAI/blob/main/docs/docs.json#L146

All done! Thanks @lorenzejay