chore(comments) Fix typo on a gitattributes comment

[raphael-riel]

Stumbled on a typo while satisfying my curiosity.
Hopefully, I'll suggest something a little more substantial next time 😄

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[mergify]

Pull Request Checklist

• Testing

• Unit test added (prefer to add a new test rather than modify existing tests)
• CLI change? Re-run/add CLI integration tests

• Documentation

• Inline docs: make sure all public APIs are documented (copy & paste from official AWS docs)
• README: update module README
• Design: for significant features, follow the design process

• Title uses the format type(scope): text

• Type: fix, feat, refactor go into CHANGELOG, chore is hidden
• Scope: name of the module without the aws- or cdk- prefix or postfix (e.g. s3 instead of aws-s3-deployment)
• Style: use all lower-case, do not end with a period

• Description

• Rationale: describe rationale of change and approach taken
• Issues: Indicate issues fixed via: fixes #xxx or closes #xxx
• Breaking?: last paragraph: BREAKING CHANGE: <describe what changed + link for details>

• Sensitive Modules (requires 2 PR approvers)

• IAM document library (in @aws-cdk/aws-iam)
• EC2 security groups and ACLs (in @aws-cdk/aws-ec2)
• Grant APIs (if not based on official documentation with a reference)

[skinny85]

Thanks so much for the contribution! And don't worry, docs are important, it's super helpful to fix these small issues :). Thanks!