docs: Add guide for organizing larger FastMCP servers with versioned tools #3769

Job	Run time
checks / pre-commit	34s
checks / readme-snippets	11s
checks / test (3.10, lowest-direct, windows-latest)	2m 10s
checks / test (3.10, lowest-direct, ubuntu-latest)	46s
checks / test (3.10, highest, windows-latest)	2m 12s
checks / test (3.10, highest, ubuntu-latest)	45s
checks / test (3.11, lowest-direct, windows-latest)	2m 9s
checks / test (3.12, lowest-direct, ubuntu-latest)	48s
checks / test (3.11, highest, windows-latest)	2m 8s
checks / test (3.11, lowest-direct, ubuntu-latest)	45s
checks / test (3.12, lowest-direct, windows-latest)	2m 55s
checks / test (3.12, highest, ubuntu-latest)	48s
checks / test (3.11, highest, ubuntu-latest)	46s
checks / test (3.13, lowest-direct, ubuntu-latest)	42s
checks / test (3.12, highest, windows-latest)	2m 50s
checks / test (3.13, lowest-direct, windows-latest)	2m 11s
checks / test (3.13, highest, windows-latest)	2m 15s
checks / test (3.13, highest, ubuntu-latest)	45s
	25m 40s

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