fix spec readme

Author: DannyBen

spec/fixtures/workspaces/completions-private/README.md

@@ -1,4 +1,4 @@
-This fixture tests that private commands are not added to the generated
-completions scripts.
+This fixture tests that private commands and flags are not added to the
+generated completions scripts.
 
 Reference issue: https://github.com/DannyBen/bashly/issues/388