Avoid writing derived dosh_host in installers

install.ps1

@@ -475,7 +475,7 @@ escape_key = "^]"
 $hostsConfig = Join-Path $configDir "hosts.toml"
 if ($ForceConfig -or -not (Test-Path $hostsConfig)) {
     $defaultServer = if ($Server) { $Server } else { "user@example.com" }
-    $hostUdp = if ($DoshHost) { $DoshHost } else { $defaultServer }
+    $hostUdpLine = if ($DoshHost) { "dosh_host = `"$DoshHost`"" } else { "# dosh_host = `"server.example.com`"" }
     @"
 # Example:
 # [server]
@@ -487,7 +487,7 @@ if ($ForceConfig -or -not (Test-Path $hostsConfig)) {
 
 [default]
 ssh = "$defaultServer"
-dosh_host = "$hostUdp"
+$hostUdpLine
 port = $Port
 predict = true
 "@ | Set-Content -NoNewline -Encoding utf8 $hostsConfig

install.sh

@@ -687,9 +687,9 @@ EOF
   if [ "$force_config" -eq 1 ] || [ ! -f "$hosts_config" ]; then
     default_server="${server:-user@example.com}"
     if [ -n "$dosh_host" ]; then
-      host_udp="$dosh_host"
+      host_udp_line="dosh_host = \"$dosh_host\""
     else
-      host_udp="$default_server"
+      host_udp_line="# dosh_host = \"server.example.com\""
     fi
     cat >"$hosts_config" <<EOF
 # Example:
@@ -702,7 +702,7 @@ EOF
 
 [default]
 ssh = "$default_server"
-dosh_host = "$host_udp"
+$host_udp_line
 port = $port
 predict = true
 EOF