Explain that the no-access team unit does not affect public repositories (#22661)

Fixes https://github.com/go-gitea/gitea/issues/22600

Add explanations to team unit access control.

---------

Co-authored-by: Jason Song <i@wolfogre.com>

options/locale/locale_en-US.ini

@@ -2432,7 +2432,7 @@ teams.leave.detail = Leave %s?
 teams.can_create_org_repo = Create repositories
 teams.can_create_org_repo_helper = Members can create new repositories in organization. Creator will get administrator access to the new repository.
 teams.none_access = No Access
-teams.none_access_helper = Members cannot view or do any other action on this unit.
+teams.none_access_helper = Members cannot view or do any other action on this unit. It has no effect for public repositories.
 teams.general_access = General Access
 teams.general_access_helper = Members permissions will be decided by below permission table.
 teams.read_access = Read