Fix: simple agent template notes

[mendonk]

• Remove youtube starter template
• Replace existing simple agent.json with updated readme, description, and key node.

[codspeed-hq]

CodSpeed Performance Report

Merging #4709 will degrade performances by 26.77%

_{Comparing fix-simple-agent-template-notes (b31bbec) with main (b978241)}

Summary

⚡ 1 improvements
❌ 2 regressions
✅ 12 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	fix-simple-agent-template-notes	Change
❌	test_successful_run_with_input_type_any	219.2 ms	299.4 ms	-26.77%
⚡	test_successful_run_with_input_type_text	217.6 ms	191.3 ms	+13.71%
❌	test_successful_run_with_output_type_debug	162.7 ms	216.5 ms	-24.86%

[ogabrielluiz]

Hey @mendonk

The conflicts are just due to formatting. If you fix them, please run the backend once to make sure the formatting is correct.

[ogabrielluiz]

Hey @mendonk there's probably something wrong with the JSON you added.