Add TestServers documentation page

docs/source/index.rst

@@ -25,7 +25,7 @@ Welcome to Pyrogram
         </a>
         <br>
         <a href="https://github.com/pyrogram/pyrogram/blob/master/compiler/api/source/main_api.tl">
-            <img src="https://img.shields.io/badge/schema-layer%2082-eda738.svg?longCache=true&colorA=262b30"
+            <img src="https://img.shields.io/badge/schema-layer%2091-eda738.svg?longCache=true&colorA=262b30"
                 alt="Scheme Layer">
         </a>
         <a href="https://github.com/pyrogram/tgcrypto">
@@ -64,7 +64,7 @@ Features
 -   **Easy to use**: You can easily install Pyrogram using pip and start building your app right away.
 -   **High-level**: The low-level details of MTProto are abstracted and automatically handled.
 -   **Fast**: Crypto parts are boosted up by TgCrypto_, a high-performance library written in pure C.
--   **Updated** to the latest Telegram API version, currently Layer 82 on top of MTProto 2.0.
+-   **Updated** to the latest Telegram API version, currently Layer 91 on top of MTProto 2.0.
 -   **Documented**: The Pyrogram API is well documented and resembles the Telegram Bot API.
 -   **Full API**, allowing to execute any advanced action an official client is able to do, and more.
 
@@ -89,6 +89,7 @@ To get started, press the Next button.
     resources/CustomizeSessions
     resources/TgCrypto
     resources/TextFormatting
+    resources/TestServers
     resources/SOCKS5Proxy
     resources/BotsInteraction
     resources/ErrorHandling

docs/source/resources/TestServers.rst

@@ -0,0 +1,39 @@
+Test Servers
+============
+
+If you wish to test your application in a separate environment, Pyrogram is able to authorize your account into
+Telegram's test servers without hassle. All you need to do is start a new session (e.g.: "my_account_test") using
+``test_mode=True``:
+
+.. code-block:: python
+
+    from pyrogram import Client
+
+    with Client("my_account_test", test_mode=True) as app:
+        print(app.get_me())
+
+.. note::
+
+    If this is the first time you login into test servers, you will be asked to register your account first.
+    Don't worry about your contacts and chats, they will be kept untouched inside the production environment;
+    accounts authorized on test servers reside in a different, parallel instance of a Telegram database.
+
+Test Mode in Official Apps
+--------------------------
+
+You can also login yourself into test servers using official desktop apps, such as Webogram and TDesktop:
+
+- **Webogram**: Login here: https://web.telegram.org/?test=1
+- **TDesktop**: Open settings and type ``testmode``.
+
+Test Numbers
+------------
+
+Beside normal numbers, the test environment allows you to login with reserved test numbers.
+Valid phone numbers follow the pattern ``99966XYYYY``, where ``X`` is the DC number (1 to 3) and ``YYYY`` are random
+numbers. Users with such numbers always get ``XXXXX`` as the confirmation code (the DC number, repeated five times).
+
+.. important::
+
+    Do not store any important or private information in such test users' accounts; anyone can make use of the
+    simplified authorization mechanism and login at any time.