docs(gateway): update diagrams for battery level support

- Add KEY_BATTERY (0x05) to class diagram
- Update EXPECTED_PAYLOAD_SIZE from 12 to 14 in class diagram
- Update payload size check from 12 to 14 in sequence diagram

doc_resources/gateway/class_diagram.puml

@@ -1,6 +1,5 @@
 @startuml
 skinparam linestyle ortho
-
 class Gateway {
     - gateway_id: str
     - mqtt_broker: str
@@ -11,8 +10,9 @@ class Gateway {
     + KEY_HUMIDITY: 0x02
     + KEY_TEMP: 0x03
     + KEY_CO2: 0x04
+    + KEY_BATTERY: 0x05
     + INVALID_VALUE: 0xFFFFFFFF
-    + EXPECTED_PAYLOAD_SIZE: 12
+    + EXPECTED_PAYLOAD_SIZE: 14
     --
     + decode_payload(data: bytes): dict
     + publish(mac: str, data: dict)
@@ -21,12 +21,10 @@ class Gateway {
     + on_publish(client, userdata, mid, reason_code, properties)
     + run()
 }
-
 class BleakScanner {
     + start()
     + stop()
 }
-
 class MQTTClient {
     + connect()
     + publish()
@@ -34,8 +32,6 @@ class MQTTClient {
     + username_pw_set()
     + loop_start()
 }
-
 Gateway o-- BleakScanner
 Gateway o-- MQTTClient
-
 @enduml

doc_resources/gateway/sequence_data_collection.puml

@@ -14,7 +14,7 @@ alt company_id != 0xffff
 else company_id == 0xffff
     gw -> gw : check payload size
 
-    alt payload size != 12 bytes
+    alt payload size != 14 bytes
         gw -> gw : discard packet\n(non-Thingy device)
     else
         gw -> gw : decode_payload()