Fixed broken URL for docker-compose.yaml

[kameshkotwani]

The previous URL was pointing to a parent directory which resulted in a 404 error as file was not present in parent directory, rather the file is present in the same directory as the page, so the URL has been fixed to point to correct location.

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^ Add meaningful description above

Read the Pull Request Guidelines for more information.
In case of fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
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[boring-cyborg]

Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contribution Guide (https://github.com/apache/airflow/blob/main/CONTRIBUTING.rst)
Here are some useful points:

• Pay attention to the quality of your code (flake8, mypy and type annotations). Our pre-commits will help you with that.
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  In case of doubts contact the developers at:
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[boring-cyborg]

Awesome work, congrats on your first merged pull request!

[kaxil]

Thanks @kameshkotwani