ui: add note for colrev package --init

colrev/package_manager/init.py

@@ -240,7 +240,7 @@ def validate_name(answers: list, name: str) -> bool:
     questions.append(
         inquirer.Checkbox(
             "plugins",
-            message="Select the plugin types",
+            message="Select the plugin types (use SPACE to select)",
             choices=list(INTERFACE_MAP.keys()),
         )
     )