Update README (#189)

Author: okue

README.rst

@@ -842,8 +842,8 @@ https://developers.line.me/en/docs/messaging-api/reference/#webhook-event-object
 
 The following classes are found in the ``linebot.models`` package.
 
-Event
-^^^^^
+`Event <https://line-bot-sdk-python.readthedocs.io/en/stable/linebot.models.html#module-linebot.models.events>`__
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 - MessageEvent
     - type
@@ -886,6 +886,30 @@ Event
         - type
         - hwid
         - device_message
+- MemberJoinedEvent
+    - type
+    - timestamp
+    - source: `Source <#source>`__
+    - reply\_token
+    - joined: Joined
+- MemberLeftEvent
+    - type
+    - timestamp
+    - source: `Source <#source>`__
+    - reply\_token
+    - left: Left
+- AccountLinkEvent
+    - type
+    - timestamp
+    - source: `Source <#source>`__
+    - reply\_token
+    - link: Link
+- ThingsEvent
+    - type
+    - timestamp
+    - source: `Source <#source>`__
+    - reply\_token
+    - things: DeviceLink | DeviceUnlink | ScenarioResult
 
 Source
 ^^^^^^
@@ -912,12 +936,17 @@ Message
 - ImageMessage
     - type
     - id
+    - content_provider
 - VideoMessage
     - type
     - id
+    - duration
+    - content_provider
 - AudioMessage
     - type
     - id
+    - duration
+    - content_provider
 - LocationMessage
     - type
     - id