reverseproxy: Minor tweaks

We'll need that context in v2.1 when the transport can manage its own
client certificates; see #3198

modules/caddyhttp/reverseproxy/command.go

@@ -121,7 +121,7 @@ func cmdReverseProxy(fs caddycmd.Flags) (int, error) {
 	urlHost := fromURL.Hostname()
 	if urlHost != "" {
 		route.MatcherSetsRaw = []caddy.ModuleMap{
-			caddy.ModuleMap{
+			{
 				"host": caddyconfig.JSON(caddyhttp.MatchHost{urlHost}, nil),
 			},
 		}