fixing directory path in README.md

[amdavidson]

Description

The path in the build instructions listed in README.md was not quite correct and did not include the pulled directory name.

Fixes #

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

This is only a documentation update, no code changes.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

[github-actions]

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[amdavidson]

I have read the CLA Document and I hereby sign the CLA