code: function findWorkspaceRoot(initial) {
    if (!initial) {
      initial = process.cwd();
    }
    let previous = null;
    let current = path.normalize(initial);
  
    do {
      const manifest = readPackageJSON(current);
      const workspaces = extractWorkspaces(manifest);
  
      if (workspaces) {
        const relativePath = path.relative(current, initial);
        if (relativePath === '' || micromatch([relativePath], workspaces).length > 0) {
          return current;
        } else {
          return null;
        }
      }
  
      previous = current;
      current = path.dirname(current);
    } while (current !== previous);
  
    return null;
  }
docs: Adapted from:
  https://github.com/yarnpkg/yarn/blob/ddf2f9ade211195372236c2f39a75b00fa18d4de/src/config.js#L612
  @param {string} [initial]
  @return {string|null}