Add multi-wavelength spectroscopy tutorial #202

Job	Run time
test-dev / Julia 1 - ubuntu-latest - default - pull_request	13m 37s
test-dev / Julia pre - ubuntu-latest - default - pull_request	7m 42s
test-dev / Julia 1.11 - ubuntu-latest - default - pull_request	5m 7s
test-dev / Julia min - ubuntu-latest - default - pull_request	6m 39s
	33m 5s

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