document usage of password argument (2)

README.md

@@ -32,7 +32,8 @@ You can also specify the arguments with declarations, which also adds the abilit
 
 - **Host**: Generally this is 127.0.0.1 (Please note, running it remotely will cause the script to take significantly longer)
 - **Port**: The port to connect to (e.g. 6379)
-- **DBNum**: The Redis to connect to (e.g. 0)
+- **Password**: The Redis password if authentication is required
+- **DBNum**: The Redis database to connect to (e.g. 0)
 - **Sample size**: This optional parameter controls how many keys to sample. I recommend starting with 10, then going to 100 initially. This
 will enable you to see that keys are being grouped properly. If you omit this parameter the script samples 10% of your keys. If the sample size is
 greater than the number of keys in the database the script will walk all the keys in the Redis database. **DO NOT** run this with a lot of keys on