Provide example devcontainer config for mdns and USB passthrough (#6094)

.devcontainer/devcontainer.json

@@ -7,8 +7,21 @@
     "PIP_BREAK_SYSTEM_PACKAGES": "1",
     "PIP_ROOT_USER_ACTION": "ignore"
   },
-  "runArgs": ["--privileged", "-e", "ESPHOME_DASHBOARD_USE_PING=1"],
+  "runArgs": [
+    "--privileged",
+    "-e",
+    "ESPHOME_DASHBOARD_USE_PING=1"
+    // uncomment and edit the path in order to pass though local USB serial to the conatiner
+    // , "--device=/dev/ttyACM0"
+  ],
   "appPort": 6052,
+  // if you are using avahi in the host device, uncomment these to allow the
+  // devcontainer to find devices via mdns
+  //"mounts": [
+  //  "type=bind,source=/dev/bus/usb,target=/dev/bus/usb",
+  //  "type=bind,source=/var/run/dbus,target=/var/run/dbus",
+  //  "type=bind,source=/var/run/avahi-daemon/socket,target=/var/run/avahi-daemon/socket"
+  //],
   "customizations": {
     "vscode": {
       "extensions": [