docs: Add config file glossary

Part of issue #118.

This commit adds a new page for a configuration file glossary. This page
is a highly-detailed overview of the config file and what each setting
does in the `env.example` file. It is intended for advanced users.

For now, this commit does not pull the duplicated parts out of
`installation.rst`, but I plan to deprecate that page in a future pull
request.

docs/config-file-glossary.rst

@@ -0,0 +1,92 @@
+####################
+Config file glossary
+####################
+
+This page is a glossary of different settings in the ``env.example`` configuration file.
+The values shown for the settings are their defaults.
+This glossary is intended for advanced users.
+
+
+************
+IRC settings
+************
+
+``IRC_BLACKLIST=""``
+    Comma-separated list of IRC nicks to ignore
+
+``IRC_BOT_NAME=teleirc``
+    IRC nickname for bot
+
+``IRC_CHANNEL=#channel``
+    IRC channel for bot to join
+
+``IRC_SEND_STICKER_EMOJI=true``
+    Send emojis associated with a sticker to IRC (when a Telegram user sends a sticker)
+
+``IRC_PREFIX="<"``
+    Text displayed before Telegram name in IRC
+
+``IRC_SUFFIX=">"``
+    Text displayed after Telegram name in IRC
+
+``IRC_SERVER=chat.freenode.net``
+    IRC server to connect to
+
+``IRC_NICKSERV_SERVICE=NickServ``
+    IRC service used for authentication
+
+``IRC_NICKSERV_PASS=""``
+    IRC account password to complete IRC authentication
+
+``IRC_EDITED_PREFIX="[EDIT] "``
+    Prefix to include when a user edits a Telegram message and it is resent to IRC
+
+``IRC_MAX_MESSAGE_LENGTH=400``
+    Maximum length of the message that can be sent to IRC.
+    Longer messages will be split into multiple messages.
+
+
+*****************
+Telegram settings
+*****************
+
+``TELEGRAM_CHAT_ID=-0000000000000``
+    Telegram chat ID of bridged group (`how do I get this? <http://stackoverflow.com/a/32572159>`_)
+
+``TELEIRC_TOKEN=000000000:AAAAAAaAAa2AaAAaoAAAA-a_aaAAaAaaaAA``
+    Private API token for Telegram bot
+
+``MAX_MESSAGES_PER_MINUTE=20``
+    Maximum number of messages sent to Telegram from IRC per minute
+
+``SHOW_ACTION_MESSAGE=true``
+    Relay action messages (e.g. ``/me thinks Teleirc is cool!``)
+
+``SHOW_JOIN_MESSAGE=false``
+    Send Telegram message when someone joins IRC channel
+
+``SHOW_KICK_MESSAGE=true``
+    Send Telegram message when someone is kicked from IRC channel
+
+``SHOW_LEAVE_MESSAGE=false``
+    Send Telegram message when someone leaves IRC channel
+
+
+**************
+Imgur settings
+**************
+
+``USE_IMGUR_FOR_IMAGES=false``
+    Upload picture messages from Telegram to Imgur, send Imgur link to IRC
+
+``IMGUR_CLIENT_ID=0000000000``
+    Imgur API client ID value to access Imgur API
+
+
+**********************
+Miscellaneous settings
+**********************
+
+``NTBA_FIX_319=1``
+    Required to fix a bug in a library used by Teleirc.
+    For context, see `yagop/node-telegram-bot-api#319 <https://github.com/yagop/node-telegram-bot-api/issues/319#issuecomment-324963294>`_.

docs/index.rst

@@ -15,6 +15,7 @@ Today, it is used by various communities.
 
    installation
    using-docker
+   config-file-glossary
    who-uses-teleirc