apache2/apache2-manual.conf

#
# This configuration file belongs to the apache2-doc package.
#
# The alias provides the manual, even if you choose to move your DocumentRoot.
# Comment this out if you do not care for the documentation.
#
AliasMatch ^/manual(?:/(?:de|en|es|fr|ja|ko|ru))?(/.*)?$ "/usr/share/apache2/manual$1"

<Directory "/usr/share/apache2/manual">
    Options Indexes
    AllowOverride None
    Require all granted

    <Files *.html>
        SetHandler type-map
    </Files>

    SetEnvIf Request_URI ^/manual/(de|en|es|fr|ja|ko|ru)/ prefer-language=$1
    RedirectMatch 301 ^/manual(?:/(de|en|es|fr|ja|ko|ru)){2,}(/.*)?$ /manual/$1$2
</Directory>