Build Directory
By default the Compute Engine builds from the root of the repository (./).
Build Directory () on a connected repository card overrides
that, pointing the build at a sub-directory of the repository instead. It opens
the Select Build Directory dialog, a tree view of the repository folders.
Pick a folder from the tree and click Set Directory to save the choice on
the repository. The Compute Engine clones the repository on the next run and
builds from the chosen directory, recursing into every sub-directory below it.
The build directory persists on the repository until you change it again. To
return to the repository root, reopen the dialog and pick ./.
See also: How to Run Code from a GitHub Repository.