Add explanation of the "flipped" printer setting and update README

README.md

@@ -21,6 +21,8 @@ cp config.toml.example config.toml
 $EDITOR config.toml
 # Put the required information into config.toml
 ```
+Besides the already mentioned API credentials the config.toml contains other (interesting) settings.
+For each setting there is a short explanation on what the setting does and what the default value is if the setting is not defined.
 
 # Printing Tweets
 ### Check your thermal printer

config.toml.example

@@ -7,4 +7,7 @@ token="PUT_YOUR_ACCESS_TOKEN_HERE"
 secret="PUT_YOUR_ACCESS_SECRET_HERE"
 
 [printer]
+# The printout can be flipped upside down. In this mode the lines will be
+# printed in reversed order. This is useful if the printer is mounted on a wall.
+# Default Value: false
 flipped=false