docs(key): 📖 addendum to rename Tonality → Key

[albertms10]

Continues #380

[coveralls]

Pull Request Test Coverage Report for Build 7604400633

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• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 7604376433:	0.0%
Covered Lines:	1072
Relevant Lines:	1072

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💛 - Coveralls