Added commands to redis chapter

docs/redis.md

@@ -8,10 +8,9 @@ To connect to the redis cli execute:
 docker-compose exec redis-mailcow redis-cli
 ```
 
-Here are some usefull commands for debugging:
+Here are some usefull commands for the redis-cli for debugging:
 
-!!! info
-    - **monitor**: Listens for all requests received by the server in real time.
+**monitor**: Listens for all requests received by the server in real time:
 ```
 # docker-compose exec redis-mailcow redis-cli
 127.0.0.1:6379> monitor
@@ -20,3 +19,18 @@ Here are some usefull commands for debugging:
 1494077288.292970 [0 172.22.1.253:41229] "SMEMBERS" "BAYES_SPAM_keys"
 [...]
 ```
+
+**keys**: Get all keys matching your pattern:
+
+```
+
+```
+
+**ping**: Test a connection
+
+```
+127.0.0.1:6379> PING
+PONG
+```
+
+If you want to know more, here is a [cheat sheet](https://www.cheatography.com/tasjaevan/cheat-sheets/redis/).