Add Heroku instructions to sessions documentation (#586)

readthedocs/extra/advanced-usage/sessions.rst

@@ -44,3 +44,52 @@ methods. For example, you could save it on a database:
 
 You should read the ````session.py```` source file to know what "relevant
 data" you need to keep track of.
+
+
+Sessions and Heroku
+-------------------
+
+You probably have a newer version of SQLite installed (>= 3.8.2). Heroku uses
+SQLite 3.7.9 which does not support ``WITHOUT ROWID``. So, if you generated
+your session file on a system with SQLite >= 3.8.2 your session file will not
+work on Heroku's platform and will throw a corrupted schema error.
+
+There are multiple ways to solve this, the easiest of which is generating a
+session file on your Heroku dyno itself. The most complicated is creating
+a custom buildpack to install SQLite >= 3.8.2.
+
+
+Generating Session File on a Heroku Dyno
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. warning::
+    Do not restart your application Dyno at any point prior to retrieving your
+    session file. Constantly creating new session files from Telegram's API
+    will result in a 24 hour rate limit ban.
+
+Due to Heroku's ephemeral filesystem all dynamically generated
+files not part of your applications buildpack or codebase are destroyed upon
+each restart.
+
+Using this scaffolded code we can start the authentication process:
+
+    .. code-block:: python
+
+        client = TelegramClient('login.session', api_id, api_hash).start()
+
+At this point your Dyno will crash because you cannot access stdin. Open your
+Dyno's control panel on the Heroku website and "run console" from the "More"
+dropdown at the top right. Enter ``bash`` and wait for it to load.
+
+You will automatically be placed into your applications working directory.
+So run your application ``python app.py`` and now you can complete the input
+requests such as "what is your phone number" etc.
+
+Once you're successfully authenticated exit your application script with
+CTRL + C and ``ls`` to confirm ``login.session`` exists in your current
+directory. Now you can create a git repo on your account and commit
+``login.session`` to that repo.
+
+You cannot ``ssh`` into your Dyno instance because it has crashed, so unless
+you programatically upload this file to a server host this is the only way to
+get it off of your Dyno.