Update btcpayserver.nix

system/bitcoin/btcpayserver.nix

@@ -1,6 +1,26 @@
+### BTCPayServer
 {
   services.btcpayserver = {
+    # Set this to enable BTCPayServer, a self-hosted, open-source
+    # cryptocurrency payment processor.
     enable = true;
+    # Privacy Warning: BTCPayServer currently looks up price rates without
+    # proxying them through Tor. This means an outside observer can correlate
+    # your BTCPayServer usage, like invoice creation times, with your IP address.
+    #
+    # Enable this option to connect BTCPayServer to clightning.
     lightningBackend = "clightning";
+    #
+    # Enable this option to connect BTCPayServert to lnd.
+    #
+    # The lightning backend service is automatically enabled.
+    # Afterwards you need to go into Store > General Settings > Lightning Nodes
+    # and select "the internal lightning node of this BTCPay Server".
+    #
   };
+  # Set this to create an onion service to make the btcpayserver web interface
+  # accessible via Tor.
+  # Security WARNING: Create a btcpayserver administrator account before allowing
+  # public access to the web interface.
+  # nix-bitcoin.onionServices.btcpayserver.enable = true;
 }