Fix broken build instructions link in README.md

[iron-condor]

Description

Found a broken link in the README.md when looking for build instructions. Fixed the path; looks like a small oversight when some files were moved in #8922. 

Reference

N/A

Checklist

• [ X ] My code follows the style guidelines for this project
• [ X ] I have not added any packages that contain high risk or unknown licenses (GPL, LGPL, MPL, etc. consult with DevOps if in question)
• [ X ] I have performed a self review of my own code
• [ X ] I have commented my code PARTICULARLY in hard to understand areas
• [ X ] I have added thorough tests where needed

[brizental]

Thanks!