Should we may be now decide on a convention to describe function arguments?

In other projects I primarily use numpy's notation (actually in in Fail2ban started to do to -- e.g. 057f0ad1357273f027b944e046d66e486c2f197f) https://github.com/numpy/numpy/blob/master/doc/HOWTO_DOCUMENT.rst.txt ,

so here it would be smth like:

```
Parameters
------------
jail : str
  Jail name
actionname: str
  Action name
host: str, optional
  SMTP host, which can include port number (in "host:port" format)
...
```