docs: add on_demand_tls server

nanospearing · web-flow · commit 5051cf884ab8 · 2024-07-21T13:22:09.000-04:00
I don't know why caddy thought this would help prevent abuse.
diff --git a/examples/web-server/caddy/Caddyfile b/examples/web-server/caddy/Caddyfile
@@ -1,3 +1,9 @@
+{
+	on_demand_tls {
+		ask http://example.com
+	}
+}
+
 coder.example.com, *.coder.example.com {
   reverse_proxy localhost:3000
   tls {
