SECRETS: Fix secrets rule in the allowed sections
    
    We have been matching an invalid subsection of the secrets' section,
    like:
    [secrets/users/]
    
    Let's ensure that we only match the following cases:
    [secrets]
    [secrets/users/[0-9]+]
    
    Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>
    
    Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>
    (cherry picked from commit da8801c363716533f60bc78e10f3a2100cebc3a1)