Added a note about a debug setting

Reviewed-on: #25

README.md

@@ -73,6 +73,34 @@ Mandatory keys to modify:
 
 After all of that you're good to go! Happy using :)
 
+## Caching
+
+Although general database access speed is fast, caching might become helpful for
+bigger servers with many bot interactions. Currently, Redis and Memcached are supported.
+
+Configuration happens through the config key `caching`.
+
+Set `caching.type` to the service of you choice ("redis" or "memcached") and then update
+the URI to access the service. It's Redis' default URI format for Redis and "address:port"
+for Memcached.
+
+Which one should I choose?
+
+| Service   | Read/write speed | Config flexibility |
+|-----------|------------------|--------------------|  
+| Redis     | High             | Very flexible      |
+| Memcached | Very high        | Basic              |
+
+> Performance difference between Redis and Memcached is generally quite low, so your setup
+> should normally depend more on the configuration flexibility than on raw speed.
+
+## Debugging
+
+There's a config key `debug` that can be set to `true` for debugging purposes.
+
+It should be set to `false` in production, otherwise log becomes very verbose and might
+contain data that shouldn't normally be logged.
+
 ## Docker [Experimental]
 
 As an experiment, Docker deployment option has been added.