clarify -F command-line option usage more

spec/build_tests_spec.rb

@@ -998,7 +998,7 @@ EOF
 
     result = run_rscons
     expect(result.stderr).to match /Failed to build/
-    expect(result.stderr).to match /^Run.*-F.*to see the failed command/
+    expect(result.stderr).to match /^Use.*-F.*to view the failed command log/
     expect(result.status).to_not eq 0
 
     result = run_rscons(rscons_args: %w[-F])