man: typo, it's DHCP not DCHP in DHCPPrefixDelegation=

(cherry picked from commit 51219be)
(cherry picked from commit db14abb)

Author: gdamjan

man/systemd.network.xml

@@ -837,7 +837,7 @@ Table=1234</programlisting></para>
           value. When enabled, prefixes configured in [IPv6Prefix] sections and routes configured in
           the [IPv6RoutePrefix] sections are distributed as defined in the [IPv6SendRA] section. If
           <varname>DHCPPrefixDelegation=</varname> is enabled, then the delegated prefixes are also
-          distributed. See <varname>DCHPPrefixDelegation=</varname> setting and the [IPv6SendRA],
+          distributed. See <varname>DHCPPrefixDelegation=</varname> setting and the [IPv6SendRA],
           [IPv6Prefix], [IPv6RoutePrefix], and [DHCPPrefixDelegation] sections for more configuration
           options.</para>
         </listitem>