put httpd-core docs in %{docdir}/httpd
    
    When httpd-core was created in d9ddc5d (Try to minimize httpd
    dependencies, 2022-03-30), the path to documentation changed.
    
    Restore documentation to %{docdir}/httpd to be consistent with past
    releases and easier for users to locate.
    
    This avoids an issue with the wrong path being listed for the example
    instance.conf in httpd.service(1).