[BUG] arp API endpoint lacks proper documentation on valid values for the ip field

[lunkwill42]

Describe the bug

This is the docstring used to generate the on-line API documentation:

nav/python/nav/web/api/v1/views.py

Lines 699 to 724 in c4199d2

	"""Lists ARP records.
	*Because the number of ARP records often is huge, the API does not support
	fetching all and will ask you to use a filter if you try.*
	Filters
	-------
	- `active`: *set this to list only records that are still active. Enabling
	this will **ignore** any start- and endtime filters present in the same
	request.*
	- `starttime`: *if set without endtime: lists all active records at that
	timestamp*
	- `endtime`: *must be set with starttime: lists all active records in the
	period between starttime and endtime*
	- `ip`
	- `mac`: *supports prefix filtering - for instance "mac=aa:aa:aa" will
	return all records where the mac address starts with aa:aa:aa*
	- `netbox`
	- `prefix`
	For timestamp formats, see the [iso8601 module
	doc](https://pypi.python.org/pypi/iso8601) and <https://xkcd.com/1179/>.
	`end_time` timestamps shown as `"9999-12-31T23:59:59.999"` denote records
	that are still active.
	"""

This lacks information about what values are valid for the ip field. In particular, it does not promote the "hidden" ability to search for subnet addresses (i.e. ip=10.0.42.0/24 is a valid filter value)

Expected behavior

The online documentation should include a paragraph about valid ip values.

Environment (please complete the following information):

• NAV version installed: 5.11.0