Add enabled documentation to config.toml

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

config.example.toml

@@ -30,6 +30,13 @@ module = "plugins.fortune"
 # By default, it will listen on all channels in the server config.
 channels = ["#fortune_telling"]
 
+# Whether this plugin is enabled.
+# If this is set to false, then the plugin won't load.
+# This is useful when you don't want to comment out an entire configuration
+# block and instead just disable it.
+# default: true
+enabled = true
+
 # The rest of this plugin block are specific to the plugin - check the plugin's
 # documentation for the values you can set.