Medusa System Added

Read about the medusa system [here](https://nadekobot.readthedocs.io/en/latest/medusa/creating-a-medusa/)

docs/medusa/snek-lifecycle.md

@@ -0,0 +1,19 @@
+# Snek Lifecycle  
+
+*You can override several methods to hook into command handler's lifecycle.  
+These methods start with `Exec*`*
+
+
+- `ExecOnMessageAsync` runs first right after any message was received  
+- `ExecInputTransformAsync` runs after ExecOnMessageAsync and allows you to transform the message content before the bot looks for the matching command  
+- `ExecPreCommandAsync` runs after a command was found but not executed, allowing you to potentially prevent command execution  
+- `ExecPostCommandAsync` runs if the command was successfully executed  
+- `ExecOnNoCommandAsync` runs instead of ExecPostCommandAsync if no command was found for a message  
+
+
+*Besides that, sneks have 2 methods with which you can initialize and cleanup your snek*  
+
+
+- `InitializeAsync` Runs when the medusa which contains this snek is being loaded  
+- `DisposeAsync` Runs when the medusa which contains this snek is being unloaded  
+