Add multi-wavelength spectroscopy tutorial #96

Job	Run time
test-release / Julia pre - ubuntu-latest - default - pull_request	24m 5s
test-release / Julia 1.11 - ubuntu-latest - default - pull_request	4m 40s
test-release / Julia 1 - ubuntu-latest - default - pull_request	6m 44s
test-release / Julia min - ubuntu-latest - default - pull_request	19m 12s
	54m 41s

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