Added listeners docs

docs/bot_tutorial/building_block_listeners.md

@@ -0,0 +1,67 @@
+# Listeners
+Listeners are a way to execute custom actions when a certain discord event happens. For example, on message creation, when a member joins or leaves a guild, or when someone changes user or nickname.
+
+## Listeners in disco
+Listeners are easy to use and implement in Disco. First of all, we'll create a [plugin](https://b1naryth1ef.github.io/disco/bot_tutorial/building_block_plugins.html) like so:
+```py
+class MyPlugin(Plugin):
+```
+Now, inside this plugin, we'll create our first listener. A listener is built up following this syntax:
+```py
+@Plugin.listen('EventName')
+def on_event_name(self, event):
+    # Do something with the event
+```
+Change the `'EventName'` in the `.listen()` method to the event name you want to listen to, and give the `on_event_name` method a more descriptive name.
+
+Now, on to adding the first listener to our plugin.
+The listener will listen for a new message and will reply with the exact same message every time. 
+```py
+@Plugin.listen('MesageCreate')
+def on_message_create(self, event):
+    event.reply(event.message.content)
+```
+Let's create a nother listener, this time one that listens for a member that's added to the guild, when this happens, it will send a welcome message in a welcome channel. For this example, we'll asume the ID for that channel's ID is stored in a constant named `WELCOME_CHANNEL`:
+```py
+@Plugin.listen('GuildMemberAdd')
+def on_member_add(self, event):
+    self.bot.client.api.channels_messages_create(
+        WELCOME_CHANNEL,
+        'Welcome to the server {}'.format(event.member.user.mention())
+    )
+```
+
+A list of all discord events supported by disco can be found [here](https://b1naryth1ef.github.io/disco/api/disco_gateway_events.html) including event attributes and functions you can use on the event property.# Listeners
+Listeners are a way to execute custom actions when a certain discord event happens. For example, on message creation, when a member joins or leaves a guild, or when someone changes user or nickname.
+
+## Listeners in disco
+Listeners are easy to use and implement in Disco. First of all, we'll create a [plugin](https://b1naryth1ef.github.io/disco/bot_tutorial/building_block_plugins.html) like so:
+```py
+class MyPlugin(Plugin):
+```
+Now, inside this plugin, we'll create our first listener. A listener is built up following this syntax:
+```py
+@Plugin.listen('EventName')
+def on_event_name(self, event):
+    # Do something with the event
+```
+Change the `'EventName'` in the `.listen()` method to the event name you want to listen to, and give the `on_event_name` method a more descriptive name and you're all set!
+
+Now, on to adding the first listener to our plugin.
+The listener will listen for a new message and will reply with the exact same message every time. 
+```py
+@Plugin.listen('MesageCreate')
+def on_message_create(self, event):
+    event.reply(event.message.content)
+```
+Let's create a nother listener, this time one that listens for a member that's added to the guild, when this happens, it will send a welcome message in a welcome channel. For this example, we'll asume the ID for that channel's ID is stored in a constant named `WELCOME_CHANNEL`:
+```py
+@Plugin.listen('GuildMemberAdd')
+def on_member_add(self, event):
+    self.bot.client.api.channels_messages_create(
+        WELCOME_CHANNEL,
+        'Welcome to the server {}'.format(event.member.user.mention())
+    )
+```
+
+A list of all discord events supported by disco can be found [here](https://b1naryth1ef.github.io/disco/api/disco_gateway_events.html) including event attributes and functions you can use on the event property.