resolve spelling mistake in tutorials docs

[DiptoChakrabarty]

Fixes #192

Changes proposed in this PR:

• Changed the spelling word as mentioned in the issue of tutorials.md file of the docs

[coveralls]

Pull Request Test Coverage Report for Build 979

• 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 99.133%

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Totals
Change from base Build 976:	0.0%
Covered Lines:	1830
Relevant Lines:	1846

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💛 - Coveralls