the commands from the `README` do not work

[amtoine]

hello there 👋

i was using your tool at work, tried to run a command very similar to the ones here but then i get an error 😮

the error

> markdown-enum foo.md foo.md
Traceback (most recent call last):
  File "/home/disc/a.stevan/.local/bin/markdown-enum", line 24, in <module>
    main()
  File "/home/disc/a.stevan/.local/bin/markdown-enum", line 11, in main
    minimal_level = int(sys.argv[2])
ValueError: invalid literal for int() with base 10: foo.md'

from the README does not work but

markdown-enum foo.md 2 foo.md

works fine and the usage is correct, only the README is not correct 😌

> markdown-enum
Usage: {} <input-markdown-file> <minimal-level> [<output-file>] 

not that harmful, just wanted to let you know 😌

Note
i started this job after the latest commit, so i think i have the latest version installed 👍