subuid: update to support LDAP

[AkihiroSuda]

rootlesscontaine.rs/content/getting-started/common/subuid.md

Lines 25 to 28 in 8185aa0

	Pre-generating all possible values for /etc/subuid and /etc/subgid, based on uid and gid, rather than the user
	and group names, is also possible. This can simplify shared management of shared computing environments
	using LDAP/AD, while there is no standardized way to store or retrieve subuid and subgid values
	from those directories.

The paragraph needs to be updated to support LDAP
https://freeipa.readthedocs.io/en/ipa-4-11/designs/subordinate-ids.html