Misleading documentation for CLI --ignore-file

[jonmarti]

The --ignore-file CLI flag only applies to advisory IDs. With current documentation that is a bit misleading. I would suggest one of the following options:

1. Enhance the documentation to specify that the flag refers only to advisory ids.
2. Change the flag name into something self-explanatory.
3. Extend the code that ignore package names so it can also take them from the --ignore-file