add short description to example and readme files

examples/webhook_examples/README.md

@@ -1,6 +1,6 @@
 # Webhook examples using pyTelegramBotAPI
 
-There are 4 examples in this directory using different libraries:
+There are 5 examples in this directory using different libraries:
 
 * **Python (CPython):** *webhook_cpython_echo_bot.py*
   * **Pros:**
@@ -42,4 +42,13 @@ There are 4 examples in this directory using different libraries:
   * **Cons:**
     * Requires Python 3.4.2+, don't work with Python 2
 
-*Latest update of this document: 2017-01-30*
+* **Twisted (20.3.0):** *webhook_twisted_echo_bot.py*
+  * **Pros:**
+    * Asynchronous event-driven networking engine
+    * Very high performance
+    * Built-in support for many internet protocols
+  * **Cons:**
+    * Twisted is low-level, which may be good or bad depending on use case
+    * Considerable learning curve - reading docs is a must.
+
+*Latest update of this document: 2020-12-17*

examples/webhook_examples/webhook_twisted_echo_bot.py

@@ -1,6 +1,12 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
+# This is an example echo bot using webhook with Twisted network framework.
+# Updates are received with Twisted web server and processed in reactor thread pool.
+# Relevant docs:
+# https://twistedmatrix.com/documents/current/core/howto/reactor-basics.html
+# https://twistedmatrix.com/documents/current/web/howto/using-twistedweb.html
+
 import logging
 import telebot
 import json