Update documentation with some fixes and MongoDB sessions

Closes #1403 and #1406.

readthedocs/basic/signing-in.rst

@@ -99,7 +99,7 @@ You will still need an API ID and hash, but the process is very similar:
 
     api_id = 12345
     api_hash = '0123456789abcdef0123456789abcdef'
-    bot_token = '12345:0123456789abcdef0123456789abcdef
+    bot_token = '12345:0123456789abcdef0123456789abcdef'
 
     # We have to manually call "start" if we want an explicit bot token
     bot = TelegramClient('bot', api_id, api_hash).start(bot_token=bot_token)

readthedocs/concepts/entities.rst

@@ -178,7 +178,7 @@ exist, which just have the ID. You cannot get the hash out of them since
 you should not be needing it. The library probably has cached it before.
 
 Peers are enough to identify an entity, but they are not enough to make
-a request with them use them. You need to know their hash before you can
+a request with them. You need to know their hash before you can
 "use them", and to know the hash you need to "encounter" them, let it
 be in your dialogs, participants, message forwards, etc.
 

readthedocs/concepts/sessions.rst

@@ -100,6 +100,9 @@ There are other community-maintained implementations available:
 * `Redis <https://github.com/ezdev128/telethon-session-redis>`_:
   stores all sessions in a single Redis data store.
 
+* `MongoDB <https://github.com/watzon/telethon-session-mongo>`_:
+  stores the current session in a MongoDB database.
+
 
 Creating your Own Storage
 =========================