Invalid PHPDOC for get_sites

[MaximeCulea]

It seems that the PHPDOC for get_sites is invalid.

While it is written that the $network_id arg allows to Limit results to those affiliated with a given network ID. Default current network ID..
In fact if we look closely to WP_Site_Query and his $network_idarg, it is specified that Limit results to those affiliated with a given network ID. If 0, include all networks. Default 0..

So when using get_sites with no network_id given, it will not return sites from the current network but from all networks.

[flixos90]

Thanks for the patch @MaximeCulea!

[SergeyBiryukov]

In 38596:

Docs: Synchronize docblocks for WP_Site_Query::__construct() and get_sites() after the changes in [37735], [38008], [38103], and [38336].

Props MaximeCulea.
Fixes #38039.