Invalid command format message for all commands with index could include the i prefix

[dlimyy]

Steps to reproduce:

editClient 7

Output Message:

Invalid command format! 
editClient: Edits the details of the client identified by the index number used in the displayed client list. Existing values will be overwritten by the input values.
Parameters: INDEX (must be a positive integer) [n/NAME] [p/PHONE] [e/EMAIL] [a/ADDRESS] [b/BIRTHDAY] [pd/PRODUCT(S)]...
Example: editClient i/1 p/91234567 e/[email protected]

Currently, in the invalid command format, INDEX could be changed to i/INDEX in the parameters as the user has to type i/INDEX for the command to work instead of just INDEX. I understand that the example includes the prefix i but it would be good to specify it in the parameters as well.