openssh: fix a 17 year old bug by using --with-mantype=doc (#419785)

Changed files
+1 -1
pkgs
tools
networking
openssh
+1 -1
pkgs/tools/networking/openssh/common.nix
···
"--sbindir=\${out}/bin"
"--localstatedir=/var"
"--with-pid-dir=/run"
-
"--with-mantype=man"
+
"--with-mantype=doc"
"--with-libedit=yes"
"--disable-strip"
(lib.withFeature withPAM "pam")