Update introduction.md

[arimal199]

fix typo

[github-actions]

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[junedev]

This typo exists in other places as well, could you please fix all occurrences?

[junedev]

@nakamura0907 Sorry, I lost track of your other PR and now that I found it again, it was not mergeble anymore. I fixed up this one and I am merging it instead.