DOCS: Update contrib instructions for Myst-nb (#11487) #21436

Job	Run time
detect ci trigger	7s
GHA Security Analysis using Zizmor	22s
cache-pixi-lock	10s
Stubtest	3m 52s
Doctests	1m 8s
Mypy 3.11	3m 16s
Minimum Version Policy	19s
Mypy	3m 29s
Pyright \| ${{ matrix.pixi-env }}"	0s
	12m 43s

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