style: add comment for pkg_npm workaround

examples/angular_bazel_architect/projects/frontend-lib/BUILD.bazel

@@ -80,5 +80,8 @@ architect_test(
 pkg_npm(
     name = "npm_package",
     package_name = "frontend-lib",
+    # This is a workaround for the Linker When using `output_dir = True`.
+    # the ':build' target dependency has an output directory so it will end up at 'npm_package/build' instead of
+    # the root of the pkg_npm output directory.
     nested_packages = [":build"],
 )