Add btmon command explanation
@@ -4,7 +4,30 @@ With the `report_unknown` option, you can collect information about new devices
`2020-12-23 17:42:12 INFO (Thread-3) [custom_components.ble_monitor] BLE ADV from UNKNOWN: RSSI: -53, MAC: 4C65A8DDB89B, ADV: 043e25020100009bb8dda8654c19020106151695fe5020aa01fe9bb8dda8654c0d1004b2007502cb`
-When sorting this data, you can find the following pattern.
+Another option is to use the following command.
+
+`btmon --write hcitrace.snoop | tee hcitrace.txt`
+
+It will display all bluetooth messages, the following is an example of a MiFlora sensor.
+
+```
+> HCI Event: LE Meta Event (0x3e) plen 41 #74 [hci0] 7.164348
+ LE Advertising Report (0x02)
+ Num reports: 1
+ Event type: Connectable undirected - ADV_IND (0x00)
+ Address type: Public (0x00)
+ Address: C4:7C:8D:6B:4F:F3 (OUI C4-7C-8D)
+ Data length: 29
+ Flags: 0x06
+ LE General Discoverable Mode
+ BR/EDR Not Supported
+ 16-bit Service UUIDs (partial): 1 entry
+ Xiaomi Inc. (0xfe95)
+ Service Data (UUID 0xfe95): 71209800b2f34f6b8d7cc40d0710035a0000
+ RSSI: -40 dBm (0xd8)
+```
+
+In the example below, we will use the data from the `report_unknown` option. When sorting this data, you can find the following pattern for the LYWSDCGQ sensor. The `Service Data` in the HCI Event above corresponds to the part from `Frame ctrl` till the `payload` (without `RSSI`).
```
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